Progressive spectacle lens having a variable refractive index and method for the design and production thereof

ABSTRACT

A progressive spectacle lens has a front face and a rear face and a uniform substrate with a locally varying refractive index. The front face and/or the rear face of the substrate is formed as a free-form surface and carries only functional coatings, if any. The refractive index varies (a) only in a first spatial dimension and in a second spatial dimension and is constant in a third spatial dimension, a distribution of the refractive being neither point-symmetrical nor axis symmetrical, or (b) in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, a distribution of the refractive index being neither point-symmetrical nor axis symmetrical, or (c) in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, a distribution of the refractive index not being point-symmetrical or axis symmetrical at all.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 17/153,595, filed Jan. 20, 2021, which is a continuationapplication of international patent application PCT/EP2019/069557, filedJul. 19, 2019, designating the United States and claiming priority fromInternational application PCT/EP2018/069806, filed Jul. 20, 2018, andthe entire content of all applications is incorporated herein byreference.

TECHNICAL FIELD

The disclosure relates to a product comprising a progressive powerspectacle lens or a representation, situated on a data medium, of theprogressive power spectacle lens having a uniform substrate with aspatially varying refractive index, a computer-implemented method fordesigning such a progressive power spectacle lens, and a method forproducing such a progressive power spectacle lens, as well as a computerprogram and a computer-readable medium for designing such a progressivepower spectacle.

BACKGROUND

In spectacle lens optics, progressive power spectacle lenses have beenknown and prevalent for decades. Like multifocal spectacle lenses(generally bifocal and trifocal spectacle lenses), these provideadditional optical power for a presbyopic user in the lower portion ofthe lens for the purposes of observing close objects, e.g., whenreading. This additional optical power is required since the lens of theeye loses its property of being able to focus on near objects more andmore with increasing age. Compared to these multifocal lenses,progressive power lenses offer the advantage of providing a continuousincrease in the optical power from the distance portion to the nearportion such that sharp vision is ensured not only in the distance andnearby, but also at all intermediate distances.

Pursuant to section 14.1.1 of DIN EN ISO 13666:2013-10, the distanceportion is that portion of a multifocal or progressive power spectaclelens that has the dioptric power for distance vision. Accordingly, thenear portion pursuant to section 14.1.3 of this standard is that portionof a multifocal or progressive power spectacle lens that has thedioptric power for near vision.

Until now, progressive power spectacle lenses have usually been producedfrom a material with a uniform constant refractive index. This meansthat the dioptric power of the spectacle lens is only set by appropriateshaping of the two surfaces, adjoining the air (front or object-sidesurface and back or eye-side surface according to the definitionsprovided in sections 5.8 and 5.9 of DIN EN ISO 13666:2013-10), of thespectacle lens. Pursuant to the definition in section 9.3 of DIN EN ISO13666:2013-10, dioptric power is the collective term for the focusingand the prismatic power of a spectacle lens.

In order to produce the continuous increase of the focusing power in aprogressive power spectacle lens made of a material with a uniformconstant refractive index, a corresponding continuous change in thesurface curvature must be present on at least one of the two spectaclelens surfaces, as also reflected in section 8.3.5 of the DIN EN ISO13666:2013-10 standard, which defines the term “progressive powerspectacle lens” as “spectacle lens with at least one progressive surfaceand an increasing (positive) power as the spectacle wearer looks down.”Pursuant to section 7.7, a progressive surface is a surface, which isnon-rotationally symmetrical, with a continuous change of curvature overpart or all of the progressive surface, generally intended to provideincreasing addition or degression power.

For a predetermined prescription, a progressive power spectacle lensthat leads to a specific design taking account of conditions of use,thickness stipulations, etc. and using a material with a constantrefractive index can be optimized according to the related art describedabove. The term design here denotes the distribution of the residualspherical and astigmatic aberrations for the spectacle wearer over theentire lens.

For this progressive power spectacle lens, it is possible to determine aprincipal line of sight, which represents the totality of all visualpoints through one of the two surfaces, e.g. the front surface or theback surface, in particular the progressive surface, as the gaze of theeye moves to object points straight ahead of the spectacle wearer fromthe distance region to the near region and for which small residualastigmatic aberrations can be achieved particularly in the intermediateportion. The intermediate portion is the entire transition regionbetween the distance portion (region for distance vision; see 14.1.1 inDIN EN ISO 13666:2013-10: part of a multifocal or progressive powerspectacle lens that has the dioptric power for distance vision) and thenear portion (region for near vision; see 14.1.3 DIN EN ISO13666:2013-10: part of a multifocal or progressive power spectacle lensthat has the dioptric power for near vision). In 14.1.2 of DIN EN ISO13666:2013-10, the intermediate portion is defined as the portion of atrifocal spectacle lens that has the dioptric power for vision at adistance that lies between the distance region and the near region.

However, owing to Minkwitz's law, the residual astigmatic aberrationswill increase in the horizontal direction alongside the principal lineof sight (owing to the increase in power in the vertical direction).

WO 89/04986 A1 initially proceeds from progressive power spectaclelenses (this document uses the expression “progressive spectaclelenses”) of the type set forth at the outset. From page 1, 2^(nd), and3^(rd) section of the document, it is possible to gather that “themanufacturing process and, more particularly, polishing” of progressivesurfaces of progressive power spectacle lenses are “difficult” onaccount of the surface form of the latter that “deviates very stronglyfrom the spherical form” and that the manufactured surface deviatesstrongly from the calculated intended form. “Moreover, it is notpossible—at least with one progressive surface—to keep the imagingaberrations and, more particularly, the astigmatism and distortion smallover the entire lens.”

On page 2 of WO 89/04986 A1, it is explained further that althoughspectacle lenses with a changing refractive index are known, therealization of progressive spectacle lenses by replacing the complicatedsurface form of the progressive surface by a varying refractive indexhas failed in the past, presumably due to the expected similarlycomplicated refractive index function thereof.

WO 89/04986 A1 claims to achieve “a simplified manufacture in the caseof comparable imaging properties if [ . . . ] a refractive index of thelens material that changes at least along the principal line of sight inthe intermediate portion at least partly contributes to the increase inthe optical power.” However, this is realized under the goal of“decreasing the differences in the radii of curvature between distanceportion and near portion such that, firstly, the processing of a blankwith spherical boundary surfaces for the purposes of manufacturing aprogressive surface is reduced” and “secondly, the polishing procedure,which substantially corresponds to that of a spherical lens in theprogressive spectacle lenses according to the related art, is simplifiedand the result of the polishing process is improved”. This is becausethe use of large-area polishing tools, the polishing surfaces of whichhad approximately the size of the progressive surface to be polished,was usual at the time of the filing date of WO 89/04986 A1.

Further, on page 5, line 15ff., the document explains: If theastigmatism is additionally also reduced along the principal meridian asa result of the variation in the refractive index, this means that therestriction when forming the spectacle lens of the surface astigmatismhaving to be small along the principal meridian or the principal line ofsight is dispensed with, and so the spectacle lens [ . . . ] is notsubject to Minkwitz's theorem and the spectacle lens can be formedsubstantially more cost-effectively under other aspects.

The declared object of this document is that of obtaining polishablesurfaces in a simple manner by virtue of the refractive index variationhaving a correspondingly complicated form. The penultimate paragraph onpage 6 expressly explains: “In the extreme case, it is even possiblehere for both surfaces of the progressive spectacle lens to be sphericalsurfaces. However, it is naturally also possible to use rotationallysymmetric aspherical surfaces.” On the other hand, the document mentionsno restrictions in respect of the complexity of the refractive indexfunction which, according to the last sentence on page 6, can be“described by means of spline functions, for example in the case of aone-dimensional function n(y) [ . . . ]”.

The document discloses two exemplary embodiments. In the secondexemplary embodiment “both the front surface and the eye-side surfaceare spherical surfaces [ . . . ]” (see ibid., page 11, last sentence).In the first exemplary embodiment, the front surface has a principalmeridian in the form of a circle (see ibid., page 10, lines 6-13) and,perpendicular thereto, it has the form of conic sections (see ibid.,page 11, lines 6-14). The back side is spherical in the first exemplaryembodiment.

In respect of the first exemplary embodiment, the document expresslyrefers [ . . . ] “to the fact that the correction of imaging aberrationshas not been taken into account during the optimization and that,nevertheless, lenses with very good imaging properties in the lateralregions have emerged. A further improvement in the imaging properties inthe regions laterally to the principal meridian is obtained by furtheroptimization of the index function”.

WO 89/12841 A1 a spectacle lens having a front boundary surface and aneye-side boundary surface and having a changing refractive index whichcontributes to the correction of the imaging aberrations.

WO 99/13361 A1 describes a so-called “MIV” lens object, which isintended to have all functional features of progressive power lenses,specifically a distance portion, a near portion and a progressive zone,but whose edge regions should be free from astigmatic aberrations. Thisdocument describes that such a lens object may comprise a sphericalfront surface and a spherical back surface. The lens object shouldcomprise a progressive zone with a refractive index that continuouslyincreases from the distance portion to the near portion. However, as arule, it is not possible to realize all desired additions in such anembodiment. Therefore, the document explains: “If desired, the range ofadditions can be bridged, in case that is impossible by the solevariable refractive index, also by manufacturing the lenses with avariable refractive index material rough block, as described above, andforming variable geometry curves as the traditional progressive lenses,thus obtaining the result of having far higher performances incomparison to the latter, because the lens, having different refractiveindexes in the different areas, provides the desired addition by usingmuch less differentiated curves between the far sight and the near sightwith a reduction of the aberration area and an increase of the usefulsight area.”

US 2010/238400 A1, from which the disclosure proceeds, describesprogressive power spectacle lenses having a plurality of layers in eachcase. At least one of the layers may have a varying refractive index,which is described with respect to two meridians that extend orthogonalto one another. Moreover, at least one of the surfaces of one of thelayers may have a progressive surface form. It describes that therefractive index profile in the horizontal direction can be used for thefull correction of any residual astigmatism resulting from the geometryof the surfaces.

Yuki Shitanoki et al.: “Application of Graded-Index for AstigmatismReduction in Progressive Addition Lens,” Applied Physics Express, Vol.2, Mar. 1, 2009, page 032401, describes, by the comparison of twoprogressive power spectacle lenses molded with the aid of the same moldshell, the fact that the astigmatism in the case of a progressive powerspectacle lens with a refractive index gradient can be reduced comparedwith a progressive power spectacle lens without a refractive indexgradient.

Particularly with regard to the distinguishability of the subject matterof the present disclosure from the multilayer spectacle lenses describedin US 2010/238400 A1, a statement is provided herewith that spectaclelenses are regularly subject to one or more finishing processes. Inparticular, functional layers are applied to one or both sides. Suchfunctional layers are layers which equip the spectacle lenses withpredetermined properties, which are advantageous to the spectacle wearerand which the spectacle lenses would not have purely on the basis of theproperties of the base or carrier material, onto which the functionallayers are applied where necessary, and the forming. In addition tooptical properties, such as an antireflection coating, silvering, lightpolarization, coloring, self-tinting etc., such advantageous propertiesalso include mechanical properties, such as hardening, reduction of theadherence of dirt or reduction in steaming up, etc., and/or electricalproperties such as shielding from electromagnetic radiation, conductionof electrical current, etc., and/or other physical or chemicalproperties. Examples of functional coatings are gathered e.g. from thedocuments WO 10/109154 A1, WO 01/55752 A1, and DE 10 2008 041 869 A1.These functional layers have no influence, or a negligible influence, onthe dioptric properties of the spectacle lens discussed within the scopeof the present patent application. The layers described in US2010/238400 A1, by contrast, have a non-negligible influence on thedioptric power of the progressive power spectacle lens.

EP 2 177 943 A1 describes a method for calculation by optimization of anoptical system, for example an ophthalmic lens, according to at leastone criterion from a list of criteria that influence a subject's visualimpression. The document proposes minimizing a cost function takingaccount of target values and criterion values. A general formula forsuch a cost function is specified. The following two examples, interalia, are specified: Paragraph [0016]: In one embodiment, the opticalworking system to be optimized comprises at least two optical surfacesand the modified parameters are at least the coefficients of theequations of two optical surfaces of the optical working system.Paragraph [0018]: In one embodiment, in which the optical system to beoptimized comprises at least two optical surfaces, the modification ofthe optical working system is carried out in such a way that at leastthe index of the optical working system is modified. It is possible tomanufacture a lens from an inhomogeneous material in which a gradient ispresent in the refractive index (this is known as a GRIN lens). By wayof example, the distribution of the optimized index can be axial orradial and/or depend on the wavelength.

WO 2011/093929 A1 discloses a progressive power spectacle lens havingtwo progressive power surfaces but a non-varying refractive index, inwhich the back surface is fashioned such that the minimum of theabsolute value of the mean curvature of the back surface is in theintermediate corridor.

EP 3 273 292 A1 describes the production of spectacle lenses usingadditive production methods.

SUMMARY

It is an object of the disclosure to provide a progressive powerspectacle lens that has further improved optical properties for thespectacle wearer compared to the progressive power spectacle lensesknown from the related art and of providing a method that can be used todesign and produce a progressive power spectacle lens with furtherimproved optical imaging properties.

This object is achieved with a product having the progressive powerspectacle lens with a uniform substrate and a spatially varyingrefractive index as disclosed herein. Further, exemplary embodiments anddevelopments are discussed below.

While WO 89/04986 A1 proposes a reduction in the complexity of therequired surface geometry by introducing a complicated but, counter toearlier assumptions, technically realizable refractive indexdistribution so as to simplify the manufacturing thereof (see ibid.,page 2, fourth paragraph, last line; page 4, first paragraph, lastsentence; page 5, first paragraph; page 5, second paragraph; page 5,last paragraph, last sentence; page 6, penultimate paragraph) and thusreduce the large deviations, which impair the optical properties, of themanufactured surface from the calculated surface (see ibid., page 1, 3rdparagraph), the inventors have recognized that this procedure does notnecessarily lead to progressive power spectacle lenses with opticalproperties that are improved for the spectacle wearer. The inventorshave recognized that the interplay of the degree of complexity of thegeometry of the progressive surface and the degree of the complexity ofthe refractive index distribution is decisive. Deviating from thesolution described in WO 89/04986 A1, the inventors therefore propose aproduct comprising a progressive power spectacle lens or arepresentation of the progressive power spectacle lens, therepresentation being situated on a data medium, or a data medium with avirtual representation of the progressive power spectacle lens. Theprogressive power spectacle lens comprises a front surface and a backsurface and a spatially varying refractive index. The front surface orthe back surface or the front and back surfaces is/are embodied as aprogressive surface. The progressive power spectacle lens isdistinguished according to the disclosure by virtue of the fact that thefront surface embodied as a progressive surface is embodied as afreeform surface or that the back surface embodied as a progressivesurface is embodied as a freeform surface or that both surfaces embodiedas progressive surfaces are embodied as freeform surfaces. Thus, thisalso includes the case where even though both surfaces, i.e., front andback surface, are embodied as progressive surfaces, only one of the twosurfaces is present as a freeform surface.

Within the scope of the present disclosure, the expression “arepresentation of a progressive power spectacle lens, the representationbeing situated on a data medium” is understood to mean, for example, arepresentation of the progressive power spectacle lens stored in amemory of a computer.

The representation of the progressive power spectacle lens comprises, inparticular, a description of the geometric form and of the medium of theprogressive power spectacle lens. By way of example, such arepresentation may comprise a mathematical description of the frontsurface, the back surface, the arrangement of these surfaces withrespect to one another (including the thickness) and the edgedelimitation of the progressive power spectacle lens, and the refractiveindex distribution of the medium of which the progressive powerspectacle lens should consist. The representation of the geometric formof the spectacle lens could also include the position of specificstructural reference points, centration points and markings for aligningthe lens (permanent marking); in this respect, see section 14.1.24 ofDIN EN ISO 13666:2012). The representation can be present in encodedform or even in encrypted form. Here, medium means thematerial/materials or the substance used to manufacture the progressivepower spectacle lens.

The representation, in particular the description of the geometric formof the progressive power spectacle lens and of the medium from which theprogressive power spectacle lens is formed, the description beingexplained in detail above, can also be transformable by a transformationinto manufacturing data for producing a progressive power spectaclelens. The representation can alternatively or additionally comprise thetransformed manufacturing data for producing the progressive powerspectacle lens.

In the context of the present disclosure, manufacturing data areunderstood to mean the data that can be loaded (i) into the drive deviceof the manufacturing machine or (ii) into the drive device or the drivedevices of the manufacturing machines, in order to manufacture theprogressive power spectacle lens with the geometric form according tothe disclosure and the medium.

In the context of the present disclosure, virtual representation isunderstood to mean a description of the geometric form and of themedium, in particular the refractive index profile thereof, of theprogressive power spectacle lens. By way of example, such arepresentation may comprise a mathematical description of the frontsurface, the back surface, the arrangement of these surfaces withrespect to one another (including the thickness) and the edge of theprogressive power spectacle lens, and the refractive index distributionof the medium of which the progressive power spectacle lens shouldconsist. The representation can be present in encoded form or even inencrypted form. Here, medium means the material/materials or thesubstance used to manufacture the progressive power spectacle lens.

Pursuant to section 5.8 of DIN EN ISO 13666:2013-10, the front surfaceor object-side surface of a spectacle lens is that surface of aspectacle lens which is intended to face away from the eye in thespectacles. Accordingly, pursuant to section 5.9 of this standard, theback surface is the eye-side surface, i.e., the surface of a spectaclelens which is intended to face the eye in the spectacles.

Pursuant to section 7.7 of DIN EN ISO 13666:2013-10, a progressivesurface is a surface, which is non-rotationally symmetrical, with acontinuous change of curvature over part or all of the surface,generally intended to provide increasing addition or degression power.According to this definition, any freeform surface is a progressivesurface, but the converse does not hold true. A continuous changeexcludes jump-like changes. Generally means, particularly within thescope of the disclosure, that the addition or the degression power canbe provided, although this need not be the case. In particular, thespatially varying refractive index can at least partly assume this taskwithin the scope of the present disclosure. The expression according towhich “the spatially varying refractive index can at least partlyprovide the addition or the degression power” includes the followingthree cases:

-   -   the spatially varying refractive index does not contribute at        all to the addition or increasing power or to the degression        power or decreasing power,    -   the spatially varying refractive index partly contributes to the        addition or to the degression power, and    -   the spatially varying refractive index provides the addition or        the degression power in its entirety.

In a broad sense, a freeform surface is understood to mean a complexsurface which, in particular, can be represented exclusively by means of(in particular piecewise) polynomial functions (in particular polynomialsplines such as, for example, bicubic splines, higher-order splines offourth order or higher, Zernike polynomials, Forbes surfaces, Chebyshevpolynomials, Fourier series, polynomial non-uniform rational B-splines(NURBS)). These should be distinguished from simple surfaces such as,for example, spherical surfaces, rotationally symmetrical asphericalsurfaces, cylindrical surfaces, toric surfaces or else the surfacesdescribed in WO 89/04986 A1, which are described as circles, at leastalong the principal meridian (cf. ibid., page 12, lines 6-13). Expresseddifferently, freeform surfaces cannot be represented in the form ofconventional regular bodies such as, for example, spherical surfaces,aspherical surfaces, cylindrical surfaces, toric surfaces or else thesurfaces described in WO 89/04986 A1 (see, e.g.,www.computerwoche.de/a/die-natur-kennt-auch-nur-freiformflaechen,1176029,retrieved on Jan. 18, 2018;www.megacad.de/kennenlernen/megacad-schulungen/schulungsinhalte/schulung-freiformflaechen.html,retrieved on Jan. 18, 2018), but for example can be representedexclusively by means of (in particular piecewise) polynomial functions(in particular polynomial splines such as, for example, bicubic splines,higher-order splines of fourth order or higher, Zernike polynomials,Forbes surfaces, Chebyshev polynomials, Fourier series, polynomialnon-uniform rational B-splines (NURBS)). Accordingly, freeform surfacesare surfaces that do not correspond to regular geometry (see, e.g.,www.infograph.de/de/nurbs, retrieved on Jan. 18, 2018;books.google.de/books?id=QpugBwAAQBAJ&pg=PA101&lpg=PA101&dq=regelgeometrie+definition&source=bl&ots=CJjmQwghvo&sig=MvsGv0sqbAVEygCaW-JQhfJ99jw&hl=de&sa=X&ved=0ahUKEwi_jcD5y-HYAhXDXCwKHUaQCBw4ChDoAQgsMAI#v=onepage&q=regelgeometrie%20definition &f=false, retrieved on Jan. 18, 2018) or that are notdescribable by means of forms of analytic geometry (see, e.g.,books.google.de/books?id=LPzBgAAQBAJ&pg=PA26&lpg=PA26&dq=regelgeometrie+definition&source=bl&ots=e1upL5jinn& sig=hUNim u8deH5x8OvCiYsa242ddn8&hl=de&sa=X&ved=0ahUKEwi_jcD5y-HYAhXDXCwKHUaQCBw4ChDoAQgvMAM#v=onepage&q=regelgeometrie%20deftnitio n&f=false, retrieved on Jan. 18, 2018).

According to the disclosure, provision is made for the freeform surfaceto be a freeform surface in the narrower sense, corresponding to section2.1.2 of the DIN SPEC 58194, dated December 2015, specifically aspectacle lens surface manufactured using freeform technology, which isdescribed mathematically within the limits of differential geometry andwhich is neither point symmetric nor axially symmetric.

In particular, moreover, in one advantageous embodiment exemplaryembodiment, the freeform surface can have not only no point symmetry andno axial symmetry, but also no rotational symmetry and no symmetry withrespect to a plane of symmetry. Even though it is expedient to removeall restrictions in respect to the surface geometry, in view ofcurrently usual requirements on the optical properties of progressivepower spectacle lenses, it is sufficient to only admit freeform surfaceswith a high degree of complexity as progressive surfaces. If, moreover,the same degree of complexity is admitted for the refractive indexdistribution over the progressive power spectacle lens, to be precise inat least two or typically three spatial dimensions, these progressivepower spectacle lenses will meet the requirements of the spectaclewearers in respect of their optical properties to the greatest possibleextent.

According to the disclosure, it is furthermore provided that theprogressive power spectacle lens comprises a uniform substrate having aspatially varying refractive index and having a front surface and a backsurface. During use as intended, the front surface and the back surfaceof the substrate either form the outer surfaces of the progressive powerspectacle lens themselves or one or both of these surfaces, frontsurface and/or back surface, is/are exclusively provided with one ormore functional coatings which either does/do not contribute at all tothe spherical equivalent of the dioptric power of the progressive powerspectacle lens or which at each point contributes/contribute less than0.004 dpt to the spherical equivalent of the dioptric power of theprogressive power spectacle lens.

According to the disclosure, the term “uniform” means that the substrateitself does not consist of a plurality of individual parts formingdiscrete interfaces.

The disclosure encompasses one of the following exemplary embodiments:

-   -   (a) The refractive index varies only in a first spatial        dimension and in a second spatial dimension and is constant in a        third spatial dimension, wherein a distribution of the        refractive index in the first spatial dimension and the second        spatial dimension has neither point symmetry nor axial symmetry.    -   (b) The refractive index changes in a first spatial dimension        and in a second spatial dimension and in a third spatial        dimension. A distribution of the refractive index in the first        spatial dimension and the second spatial dimension in all planes        perpendicular to the third spatial dimension has neither a point        symmetry nor an axial symmetry.    -   (c) The refractive index changes in a first spatial dimension        and in a second spatial dimension and in a third spatial        dimension. A distribution of the refractive index has no point        symmetry and no axial symmetry at all.

In one exemplary embodiment exemplary embodiment of the disclosure, thethird spatial dimension in case (a) or (b) extends in a direction which

-   -   differs by not more than 5° from the zero viewing direction        during use as intended or    -   differs by not more than 10° from the zero viewing direction        during use as intended or    -   differs by not more than 20° from the zero viewing direction        during use as intended or    -   differs by not more than 5° from the principal viewing direction        during use as intended or    -   differs by not more than 10° from the principal viewing        direction during use as intended or    -   differs by not more than 20° from the principal viewing        direction during use as intended or    -   differs by not more than 5° from the direction of the normal        vector of the front surface in the geometric center of the        progressive power spectacle lens or    -   differs by not more than 10° from the direction of the normal        vector of the front surface in the geometric center of the        progressive power spectacle lens or    -   differs by not more than 20° from the direction of the normal        vector of the front surface in the geometric center of the        progressive power spectacle lens or    -   differs by not more than 5° from the direction of the normal        vector at the prismatic measurement point or    -   differs by not more than 10° from the direction of the normal        vector at the prismatic measurement point or    -   differs by not more than 20° from the direction of the normal        vector at the prismatic measurement point or    -   differs by not more than 5° from the direction of the normal        vector at the centration point or    -   differs by not more than 10° from the direction of the normal        vector at the centration point or    -   differs by not more than 20° from the direction of the normal        vector at the centration point.

The prismatic measurement point is a point on the front surface which isspecified by the manufacturer according to DIN EN ISO13666:2013-10-14.2.12 (in the case of a progressive power spectacle lensor a progressive power spectacle lens blank) and at which the prismaticpowers of the finished lens must be determined. The definition of thecentration point is found in section 5.20 in DIN EN ISO 13666:2013-10.

In a further exemplary embodiment of the disclosure, it is provided that

-   -   (i) the front surface embodied as a freeform surface is        fashioned such that the maximum of the absolute value of the        mean curvature of the front surface is in the intermediate        corridor, and/or    -   (ii) the back surface embodied as a freeform surface is        fashioned such that the minimum of the absolute value of the        mean curvature of the back surface is in the intermediate        corridor, or    -   (iii) the back surface has a spherical, rotationally        symmetrically aspheric or toric surface geometry and the front        surface embodied as a freeform surface is fashioned such that        the maximum of the absolute value of the mean curvature of the        front surface is in the intermediate corridor, or    -   (iv) the front surface has a spherical, rotationally        symmetrically aspheric or toric surface geometry and the back        surface embodied as a freeform surface is fashioned such that        the minimum of the absolute value of the mean curvature of the        back surface is in the intermediate corridor, or    -   (v) the back surface is not embodied as a freeform surface and        the front surface embodied as a freeform surface is fashioned        such that the maximum of the absolute value of the mean        curvature of the front surface is in the intermediate corridor,        or    -   (vi) the front surface is not embodied as a freeform surface and        the back surface embodied as a freeform surface is fashioned        such that the minimum of the absolute value of the mean        curvature of the back surface is in the intermediate corridor.

Here, pursuant to DIN EN ISO 13666:2013-10, section 14.1.25, theintermediate corridor is the region of a progressive power spectaclelens providing clear vision for ranges intermediate between distance andnear.

Such surfaces can be manufactured with very high accuracy using thecurrently available production processes. Advantages during themanufacturing emerge, in particular, when this surface geometry ischosen for the front surface. The abrasion due to polishing whencurrently conventional polishing tools, whose at least approximatelyspherical polishing surface corresponds to approximately a third of thespectacle lens surface to be polished, are used can be kept sufficientlyhomogeneous over the spectacle lens surface to be polished such that thedeviation from the calculated spectacle lens geometry is comparativelysmall. Consequently, the deviation of the actual optical properties fromthe calculated optical properties of the spectacle lens is very small.

A further exemplary embodiment of the disclosure is wherein theprogressive power spectacle lens according to the disclosure is formedin such a way that it has more advantageous optical properties describedbelow for the progressive power spectacle wearer in relation to acomparison progressive power spectacle lens, which has no spatialrefractive index variation but an identical distribution of thespherical equivalent.

A statement that a spectacle lens is designed for a predeterminedarrangement in front of an eye of a spectacle lens wearer and for one ormore predetermined object distances, at which the spectacle lens wearershould perceive an object in focus, is provided for explanatorypurposes. The spectacle lens is worthless or the optical quality is veryrestricted for the spectacle wearer in the case of an arrangementdeviating therefrom in front of the eye of the spectacle wearer and forother object distances. This applies even more to progressive powerspectacle lenses. Accordingly, a progressive power spectacle lens isonly characterized by way of the knowledge of the predeterminedarrangement in front of the eye of the spectacle wearer. Expresseddifferently, the knowledge of the arrangement of the spectacle lens interms of location and alignment in space in relation to the eye isnecessary but also sufficient to characterize the spectacle lens inone-to-one fashion in terms of the optical power thereof for thespectacle wearer. Moreover, an optician is only able to insert thespectacle lens into a spectacle frame with the correct positioning ifthey are aware of the arrangement of the spectacle lens in terms oflocation and alignment in relation to the eye of the spectacle wearer. Arepresentation of the predetermined arrangement of the progressive powerspectacle lens in front of an eye of a progressive power spectaclewearer, for whom the progressive power spectacle lens is intended, istherefore an inseparable component of the product or of the commercialware of a “progressive power spectacle lens.”

For the purposes of ensuring an arrangement with the correct positionand orientation in the progressive power spectacle lens by the optician,the manufacturer attaches permanently present markings. From DIN EN ISO13666:2013-10, section 14.1.24, it is possible to gather that these arereferred to as markings for alignment or permanent markings and thatthese were attached by the manufacturer to establish the horizontalorientation of the spectacle lens [ . . . ] or to re-establish otherreference points. Pursuant to section 6.1 of DIN EN ISO 14889:2009, themanufacturer of uncut finished spectacle lenses must facilitate anidentification by statements on the individual packaging or in anaccompanying document. In particular, there should be correction valuesfor use situations, the near addition power, the type designation or thebrand name and the necessary information to measure the addition power.The underlying object distance model used by the manufacturer of theprogressive power spectacle lens emerges from the type designation orthe brand name. The object distance for the distance or near region ispossibly also an ordering parameter that can or must be specified by theoptician. According to 3.1 of this standard, the manufacturer should beunderstood to be a natural person or legal entity who commerciallydistributes the uncut finished spectacle lens.

In this exemplary embodiment according to the disclosure, the productfurther comprises a representation, situated on a data medium, of apredetermined arrangement of the progressive power spectacle lens infront of an eye of a progressive power spectacle wearer, for whom theprogressive power spectacle lens is intended. As already explained, theprogressive power spectacle lens embodied according to the disclosure(not only) in this exemplary embodiment has a distribution of aspherical equivalent for the predetermined arrangement of theprogressive power spectacle lens in front of the eye of the progressivepower spectacle wearer, for whom the progressive power spectacle lens isintended. Further, the progressive power spectacle lens embodiedaccording to the disclosure comprises an intermediate corridor with awidth. The progressive power spectacle lens designed according to thisexemplary embodiment according to the disclosure has a refractive indexthat varies spatially in such a way that the width of the intermediatecorridor of the progressive power spectacle lens, at least in a section(e.g. in a horizontal section or in the region of the intermediatecorridor in which the increase in power is between 25% and 75% of theaddition, or over the entire length; the width of the intermediatecorridor at the beginning and at the end of the intermediate corridorsometimes also depends on the configuration of the distance or nearportion) or over the entire length of the intermediate corridor, isgreater than the width of the intermediate corridor of a comparisonprogressive power spectacle lens for the same prescription and in thecase of the same object distance model with the same distribution of thespherical equivalent in the case of the same arrangement of thecomparison progressive power spectacle lens in front of the eye of theprogressive power spectacle wearer, but with a spatially non-varyingrefractive index.

Here, the term “spherical equivalent” is defined as the arithmetic meanof the focusing power, as emerges, for example, from Albert J. Augustin:Augenheilkunde. 3rd, completely reworked and extended edition. Springer,Berlin et al. 2007, ISBN 978-3-540-30454-8, p. 1272 or Heinz Diepes,Ralf Blendowske: Optik and Technik der Brille. 1st edition, OptischeFachveröffentlichung GmbH, Heidelberg 2002, ISBN 3-922269-34-6, page482:

spherical equivalent=sphere+½×cylinder

Pursuant to section 9.2 of DIN EN ISO 13666:2013-10, focal power is thecollective term for the spherical and astigmatic powers of a spectaclelens. In the equation, the spherical power is abbreviated by “sphere”;the astigmatic power is represented by “cylinder”. The term meanspherical power is also used for the term spherical equivalent.

Pursuant to DIN EN ISO 13666:2013-10, section 14.1.25, the intermediatecorridor—as already explained above—is the region of a progressive powerspectacle lens providing clear vision for ranges intermediate betweendistance and near. The principal line of sight, which represents thetotality of all visual points through one of the two delimitingsurfaces, i.e. the front surface or the back surface, of the progressivepower spectacle lens during the gazing movement of the eye on objectpoints straight in front of the spectacle wearer from distance to near,extends through the center of the intermediate corridor. The principalline of sight is regularly assumed on the front surface. Expresseddifferently, the principal line of sight denotes that line on the frontsurface of a spectacle lens that interconnects the principal visualpoints through the progressive power lens for distance and near visionand on which the intersection points of the visual rays for intermediatedistances lie in the “straight-ahead” direction (Note: the use of theback surface as a reference surface on which the principal line of sightlies is rather unusual). Regularly, the principal line of sight is aline extending approximately perpendicular in the distance and nearportion and a line extending in twisted fashion in the intermediatecorridor, i.e., the portion of the progressive power spectacle lens thathas the dioptric power for vision at ranges intermediate betweendistance and near. By way of example, the length of the intermediatecorridor can arise from the positions of the distance and near designreference points or from the positions of the distance and nearreference points. Pursuant to 5.13 of DIN EN ISO 13666:2013-10, thedistance design reference point is that point, stipulated by themanufacturer, on the front surface of a finished lens or on the finishedsurface of a lens blank, at which the design specifications for thedistance portion apply. Accordingly, pursuant to 5.14 of this standard,the near design reference point is that point, stipulated by themanufacturer, on the front surface of a finished lens or on the finishedsurface of a lens blank, at which the design specifications for the nearportion apply. Pursuant to 5.15, the distance reference point or themajor reference point is that point on the front surface of a spectaclelens at which the dioptric power for the distance portion must beachieved and, pursuant to 5.17, the near visual point is the assumedposition of the visual point on a lens, which is used for near visionunder given conditions.

In principle, the properties of the progressive power spectacle lens canbe set and determined one-to-one in relation to a comparison progressivepower spectacle lens on the basis of the specifications provided above.A simple criterion arises if the assumption is made that the at leastone section is an exemplary embodiment of the group:

-   -   horizontal section,    -   section at half addition (more particularly on the principal        line of sight),    -   horizontal section at half addition (more particularly on the        principal line of sight),    -   horizontal section at half addition (more particularly on the        principal line of sight) and horizontal section at 25% of the        addition (more particularly on the principal line of sight),    -   horizontal section at half addition (more particularly on the        principal line of sight) and horizontal section at 75% of the        addition (more particularly on the principal line of sight),    -   horizontal section at half addition (more particularly on the        principal line of sight) and horizontal section at 25% of the        addition (more particularly on the principal line of sight) and        horizontal section at 75% of the addition (more particularly on        the principal line of sight).

In section 14.2.1, DIN EN ISO 13666:2013-10 defines the addition poweras a difference between the vertex power of the near portion and thevertex power of the distance portion, measured under specifiedconditions. This standard specifies that corresponding measuring methodsare contained in the decisive standard for spectacle lenses. As thedecisive standard, DIN EN ISO 13666:2013-10 refers to DIN EN ISO8598-1:2012: “Optics and optical instruments—Focimeters—Part 1: Generalpurpose instruments”. In DIN EN ISO 13666:2013-10, section 9.7, thevertex power is defined as follows. A distinction is made between theback vertex power, defined as the reciprocal of the paraxial back vertexfocal length measured in meters, and the front vertex power, defined asthe reciprocal of the paraxial front vertex focal length measured inmeters. It is noted that, according to ophthalmic convention, the backvertex power is specified as the “power” of a spectacle lens but thefront vertex power is also required for certain purposes, e.g. in themeasurement of addition power in some multifocal and progressive powerspectacle lenses.

A further exemplary embodiment of defining the properties of theprogressive power spectacle lens by way of a comparison with theproperties of a comparison progressive power spectacle lens withproperties that are predeterminable one-to-one, namely the samedistribution of the spherical equivalent over the lens under the sameposition of the spectacle lens in front of the eye of the sameprogressive power spectacle wearer on the basis of the same objectdistance model, consists of the product further comprising

-   -   (i) a representation, situated on a data medium, of a residual        astigmatism distribution for the predetermined arrangement of        the progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (ii) a representation, situated on a data medium, of an        astigmatic power distribution, required for a full correction,        for the predetermined arrangement of the progressive power        spectacle lens in front of the eye of the progressive power        spectacle wearer, for whom the progressive power spectacle lens        is intended, and/or    -   (iii) a representation, situated on a data medium, of a        prescription and an object distance model for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of a progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (iv) a representation, situated on a data medium, of a        distribution of the spherical equivalent for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of the progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended.

In this exemplary embodiment of a progressive power spectacle lensaccording to the disclosure comprising a distance portion and a nearportion, the width of the intermediate corridor is defined by thedimension transverse to a longitudinal direction of the intermediatecorridor extending between the distance portion and near portion, withinwhich the absolute value of the residual astigmatism lies below apredetermined limit value, which is selected within a range from thegroup specified below:

-   -   (a) the limit value lies in the range between 0.25 dpt and 1.5        dpt,    -   (b) the limit value lies in the range between 0.25 dpt and 1.0        dpt,    -   (c) the limit value lies in the range between 0.25 dpt and 0.75        dpt,    -   (d) the limit value lies in the range between 0.25 dpt and 0.6        dpt,    -   (e) the limit value lies in the range between 0.25 dpt and 0.5        dpt,    -   (f) the limit value is 0.5 dpt.

Residual astigmatism is understood to be the astigmatism (according toabsolute value and axis direction) by which the astigmatism or theastigmatic power of the progressive power spectacle lens deviates fromthe astigmatic power required for a full correction at a respectivelocation on a progressive power spectacle lens surface for a beamintersecting the progressive power spectacle lens at this location forthe progressive power spectacle wearer, for whom the progressive powerspectacle lens is intended, when the progressive power spectacle wearerwears the progressive power spectacle lens as intended (such that it isarranged in front of the eye of the progressive power spectacle wearerin predetermined fashion). The term “distribution” clarifies that thisresidual astigmatism can be different locally over the spectacle lensand, as a rule, will actually be different.

Expressed differently, a residual astigmatism is understood to mean thedeviation of the astigmatic power (actual astigmatic power) of theprogressive power spectacle lens from the “prescribed” astigmatic powerin respect of absolute value and axis position. Expressed differently,the residual astigmatism is the difference, depending on the directionof view, between the actual astigmatic power and the intended astigmaticpower for the wearer of the progressive power spectacle lens in the useposition. In the use position, the position and orientation of thespectacle lens with respect to the eye when used as intended is takeninto account. The direction of view-dependence of the astigmatic powercan result, in particular, from the direction of view-dependence of theobject distance and the direction of view-dependence of the astigmaticpower of the eye. The expression “prescribed power” should therefore beunderstood in the broadest sense as an intended power that the spectaclelens should have on account of its underlying position and orientationin relation to the eye, for the respective direction of view and thedistance at which the spectacle wearer should see the object in focusfor this direction of view.

For the specific calculation of the residual astigmatism distribution(or other aberration distributions, such as, e.g., the sphericalaberration distribution or other aberration distributions of higherorder described in, e.g., EP 2 115 527 B1 or actual power distributions,such as, e.g., the actual astigmatic power, the actual spherical poweror the actual prismatic power), the vertex distance, the pupillarydistance, the pantoscopic tilt of the spectacle lens, the face formangle of the spectacle lens and the spectacle lens size, including, inparticular, the thickness and/or the edge (edge profile), too, forexample, are regularly taken into account. Furthermore, this isregularly based on an object distance model which describes the positionof object points in the spectacle wearer's field of view relative to thecenters of rotation of the wearer's eyes.

The residual astigmatism distribution can already be present as acalculated mathematical description (like in case (i)) or it can beascertained from the prescription and an object distance model (like incase (iii)) or from an already calculated astigmatic power distributionfor a full correction (like in case (ii)).

In addition to conventional refraction values, the prescription may alsocomprise further physiological parameters inherent to the spectaclewearer (i.e., generally those parameters that are inherent to thespectacle wearer) and the use conditions (i.e., generally thoseparameters that are assignable to the surroundings of the spectaclewearer) under which the prescribed progressive power spectacle lensshould be worn. The inherent physiological parameters include, interalia, the refractive error, the accommodation capability and the(possibly monocular) pupillary distance of the spectacle wearer. The useconditions include information about the seat of the lenses in front ofthe eye and also data that characterize the object distance model, suchas, e.g., whether these should be spectacles for working in front of ascreen, which are based on a distance deviating from infinity for thedistance direction of view of an object, specifically the screen.Certain standard values are assumed for the case where the individuallymeasured or determined prescription does not contain certain useconditions (e.g., a standard pantoscopic tilt of 9°).

The object distance model is understood to mean an assumption fordistances in space at which the spectacle wearer should see objects infocus. An object distance model can be characterized e.g. by thedistribution of the object distances from the front side of thespectacle lens over the different directions of view or for the pointsof intersection of the rays through the front surface. The objectposition is generally related to the center of rotation of the eyes inthe object distance model, as already explained above.

The model calculation can take account of the fact that the power andaxis position of the eye changes in the case of different objectdistances and directions of view. In particular, the model calculationcan take account of Listing's law. By way of example, the modelcalculation can also take account of the change in the astigmatic powerof the eye for near and distance, for example in the way described in DE10 2015 205 721 A1.

Within the scope of the present disclosure, a full correction describesa correction caused by wearing the progressive power spectacles asintended which, taking account of the visual properties of their eyerepresented by the prescription, allows the progressive power spectaclewearer to see in focus objects arranged at the distances on which theobject distance model is based.

For the sake of completeness, reference is made to the fact that thedata medium on which the predetermined representation is situated mayalso be, for example, a sheet of paper instead of a memory of acomputer. This relates, in particular, to the aforementioned case (iii),in which the prescription may also be noted on a sheet of paper.

A further embodiment of the product according to the disclosurecomprises the following constituent parts:

a representation, situated on a data medium, of a predeterminedarrangement of the progressive power spectacle lens in front of an eyeof a progressive power spectacle wearer, for whom the progressive powerspectacle lens is intended, and

one or more of the following representations on a data medium:

-   -   (i) a representation, situated on a data medium, of a residual        astigmatism distribution for the predetermined arrangement of        the progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (ii) a representation, situated on a data medium, of an        astigmatic power distribution, required for a full correction,        for the predetermined arrangement of the progressive power        spectacle lens in front of the eye of the progressive power        spectacle wearer, for whom the progressive power spectacle lens        is intended, and/or    -   (iii) a representation, situated on a data medium, of a        prescription and an object distance model for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of a progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (iv) a representation, situated on a data medium, of a        distribution of the spherical equivalent for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of the progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended.

The progressive power spectacle lens according to this embodiment has adistribution of a spherical equivalent for the predetermined arrangementof the progressive power spectacle lens in front of the eye of theprogressive power spectacle wearer, for whom the progressive powerspectacle lens is intended. In this embodiment, the refractive index ofthe progressive power spectacle lens varies in space in such a way thatthe maximum value of the residual astigmatism of the progressive powerspectacle lens is less than the maximum value of the residualastigmatism of a comparison progressive power spectacle lens, for thesame prescription, with the same distribution of the sphericalequivalent in the case of the same arrangement of the comparisonprogressive power spectacle lens in front of the eye of the progressivepower spectacle wearer and with the same object distance model, but witha spatially non-varying refractive index.

According to this embodiment of the disclosure, the optical propertiesof the progressive power spectacle lens perceivable by the spectaclewearer are improved over all conventional progressive power spectaclelenses.

Another exemplary embodiment of the product according to the disclosurecomprises the constituent parts specified below:

a representation, situated on a data medium, of a predeterminedarrangement of the progressive power spectacle lens in front of an eyeof a progressive power spectacle wearer, for whom the progressive powerspectacle lens is intended, at least one of the followingrepresentations on a data medium:

-   -   (i) a representation, situated on a data medium, of a residual        astigmatism distribution for the predetermined arrangement of        the progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (ii) a representation, situated on a data medium, of an        astigmatic power distribution, required for a full correction,        for the predetermined arrangement of the progressive power        spectacle lens in front of the eye of the progressive power        spectacle wearer, for whom the progressive power spectacle lens        is intended, and/or    -   (iii) a representation, situated on a data medium, of a        prescription and an object distance model for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of a progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (iv) a representation, situated on a data medium, of a        distribution of the spherical equivalent for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of the progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended.

The progressive power spectacle lens according to this embodimentexemplary embodiment has a distribution of a spherical equivalent forthe predetermined arrangement of the progressive power spectacle lens infront of the eye of the progressive power spectacle wearer, for whom theprogressive power spectacle lens is intended. The progressive powerspectacle lens comprises an intermediate corridor. The refractive indexof the progressive power spectacle lens varies in space in such a waythat, for a predetermined residual astigmatism value A_(res,lim) fromthe group

-   -   (a) the residual astigmatism value A_(res,lim) lies in the range        between 0.25 dpt and 1.5 dpt,    -   (b) the residual astigmatism value A_(res,lim) lies in the range        between 0.25 dpt and 1.0 dpt,    -   (c) the residual astigmatism value A_(res,lim) lies in the range        between 0.25 dpt and 0.75 dpt,    -   (d) the residual astigmatism value A_(res,lim) lies in the range        between 0.25 dpt and 0.6 dpt,    -   (e) the residual astigmatism value A_(res,lim) lies in the range        between 0.25 dpt and 0.5 dpt,    -   (f) the residual astigmatism value A_(res,lim) is 0.5 dpt

on a horizontal section at the narrowest point of the intermediatecorridor (e.g., where the isoastigmatism lines for 1 dpt have thesmallest distance from one another) or on a horizontal section throughthe point on the principal line of sight at which the half addition isachieved, the following relationship applies within a region with ahorizontal distance of 10 mm on both sides of the principal line ofsight:

$B > {c \times \frac{A_{{res},\lim}}{{grad}\mspace{14mu} W}}$

where grad W describes the power gradient of the spherical equivalent inthe direction of the principal line of sight of the progressive powerspectacle lens at the point on the principal line of sight at thenarrowest point of the intermediate corridor or in the point on theprincipal line of sight at which the half addition is achieved, Bdescribes the width of the region in the progressive power spectaclelens in which the residual astigmatism is A_(res)≤A_(res,lim), where cis a constant selected from the group:

-   -   (g) 1.0<c    -   (h) 1.1<c    -   (i) 1.2<c    -   (j) 1.3<c.

According to this exemplary embodiment of the disclosure, the opticalproperties of the progressive power spectacle lens perceivable by thespectacle wearer are improved over all conventional progressive powerspectacle lenses.

A further exemplary embodiment of a product according to the disclosurecomprises (i) a progressive power spectacle lens or (ii) arepresentation of the progressive power spectacle lens, therepresentation being situated on a data medium, or (iii) a data mediumwith a virtual representation of the progressive power spectacle lens,wherein the progressive power spectacle lens has a front surface and aback surface, and a spatially varying refractive index. Either the frontsurface or the back surface or both surfaces are embodied as progressivesurfaces. The front surface embodied as progressive surface is embodiedaccording to the disclosure as a freeform surface and/or the backsurface embodied as a progressive surface is embodied according to thedisclosure as a freeform surface.

The progressive power spectacle lens consists of a substrate comprisingno individual layers, and a front surface coating, comprising one ormore individual layers, on the front surface of the substrate and/or aback surface coating, comprising one or more individual layers, on theback surface of the substrate. Only the substrate has the spatiallyvarying refractive index.

According to the disclosure, a difference between the sphericalequivalent measured at each point on the front surface of theprogressive power spectacle lens with the front surface coating and/orthe back surface coating and the spherical equivalent measured at eachcorresponding point on the front surface of a comparison progressivepower spectacle lens without front surface coating and without backsurface coating but with an identical substrate (with identical geometryand identical refractive index) is less than a value from the groupspecified below:

-   -   (a) the difference value is less than 0.001 dpt    -   (b) the difference value is less than 0.002 dpt    -   (c) the difference value is less than 0.003 dpt    -   (d) the difference value is less than 0.004 dpt.

Naturally, this exemplary embodiment may also have one or more of thefeatures described above.

A first development of the product described directly above is whereinat least one of the freeform surfaces has no point symmetry and no axialsymmetry or in that at least one of the freeform surfaces has no pointsymmetry and no axial symmetry and no rotational symmetry and nosymmetry with respect to a plane of symmetry.

A second development, optionally combined with the first, is wherein

-   -   (a) the refractive index varies only in a first spatial        dimension and in a second spatial dimension and is constant in a        third spatial dimension, wherein a distribution of the        refractive index in the first spatial dimension and the second        spatial dimension has neither point symmetry nor axial symmetry,        or    -   (b) the refractive index varies in a first spatial dimension and        in a second spatial dimension and in a third spatial dimension,        wherein a distribution of the refractive index in the first        spatial dimension and the second spatial dimension in all planes        perpendicular to the third spatial dimension has neither point        symmetry nor axial symmetry, or    -   (c) the refractive index varies in a first spatial dimension and        in a second spatial dimension and in a third spatial dimension,        wherein a distribution of the refractive index has no point        symmetry and no axial symmetry at all.

The third spatial dimension in case (a) or in case (b) typically extendsin a direction which

-   -   differs by not more than 5° from the zero viewing direction        during use as intended or    -   differs by not more than 10° from the zero viewing direction        during use as intended or    -   differs by not more than 20° from the zero viewing direction        during use as intended or    -   differs by not more than 5° from the principal viewing direction        during use as intended or    -   differs by not more than 10° from the principal viewing        direction during use as intended or    -   differs by not more than 20° from the principal viewing        direction during use as intended or    -   differs by not more than 5° from the direction of the normal        vector of the front surface in the geometric center of the        progressive power spectacle lens or    -   differs by not more than 10° from the direction of the normal        vector of the front surface in the geometric center of the        progressive power spectacle lens or    -   differs by not more than 20° from the direction of the normal        vector of the front surface in the geometric center of the        progressive power spectacle lens or    -   differs by not more than 5° from the direction of the normal        vector at the prismatic measurement point or    -   differs by not more than 10° from the direction of the normal        vector at the prismatic measurement point or    -   differs by not more than 20° from the direction of the normal        vector at the prismatic measurement point or    -   differs by not more than 5° from the direction of the normal        vector at the centration point or    -   differs by not more than 10° from the direction of the normal        vector at the centration point or    -   differs by not more than 20° from the direction of the normal        vector at the centration point.

In a further configuration, the progressive power spectacle lenscomprises an intermediate corridor. In the progressive power spectaclelens it may be the case that

-   -   (i) the front surface embodied as freeform surface is fashioned        such that the mean curvature has a maximum in the intermediate        corridor, and/or    -   (ii) the back surface embodied as freeform surface is fashioned        such that the mean curvature has a minimum in the intermediate        corridor, or    -   (iii) the back surface has a spherical, rotationally        symmetrically aspheric or toric surface geometry and the front        surface embodied as a freeform surface is fashioned such that        the maximum of the absolute value of the mean curvature of the        front surface is in the intermediate corridor, or    -   (iv) the front surface has a spherical, rotationally        symmetrically aspheric or toric surface geometry and the back        surface embodied as a freeform surface is fashioned such that        the minimum of the absolute value of the mean curvature of the        back surface is in the intermediate corridor, or    -   (v) the back surface is not embodied as a freeform surface and        the front surface embodied as a freeform surface is fashioned        such that the maximum of the absolute value of the mean        curvature of the front surface is in the intermediate corridor,        or    -   (vi) the front surface is not embodied as a freeform surface and        the back surface embodied as a freeform surface is fashioned        such that the minimum of the absolute value of the mean        curvature of the back surface is in the intermediate corridor.

The product described above can additionally comprise (i) arepresentation, situated on a data medium, of a predeterminedarrangement of the progressive power spectacle lens in front of an eyeof a progressive power spectacle wearer, for whom the progressive powerspectacle lens is intended, (ii) a data medium with data concerning apredetermined arrangement of the progressive power spectacle lens infront of an eye of a progressive power spectacle wearer, wherein

-   -   the progressive power spectacle lens has a distribution of a        spherical equivalent for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and wherein    -   the progressive power spectacle lens has an intermediate        corridor with a width and in that the refractive index of the        progressive power spectacle lens varies in space in such a way        that the width of the intermediate corridor of the progressive        power spectacle lens, at least in a section or over the entire        length of the intermediate corridor, is greater than the width        of the intermediate corridor of a comparison progressive power        spectacle lens with the same distribution of the spherical        equivalent in the case of the same arrangement of the comparison        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, but with a spatially        non-varying refractive index.

The last-described configuration of the product, in a furtherconfiguration, can be wherein an exemplary embodiment of the group:

-   -   horizontal section,    -   section at half addition,    -   horizontal section at half addition,    -   horizontal section at half addition and horizontal section at        25% of the addition,    -   horizontal section at half addition and horizontal section at        75% of the addition,    -   horizontal section at half addition and horizontal section at        25% of the addition and horizontal section at 75% of the        addition, is chosen for the at least one section.

Alternatively or additionally, the product can further comprise:

-   -   (i) a representation, situated on a data medium, of a residual        astigmatism distribution for the predetermined arrangement of        the progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (ii) a representation, situated on a data medium, of an        astigmatic power distribution, required for a full correction,        for the predetermined arrangement of the progressive power        spectacle lens in front of the eye of the progressive power        spectacle wearer, for whom the progressive power spectacle lens        is intended, and/or    -   (iii) a representation, situated on a data medium, of a        prescription and an object distance model for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of a progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (iv) a representation, situated on a data medium, of a        distribution of the spherical equivalent for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of the progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (v) a data medium with data concerning a residual astigmatism        distribution for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (vi) a data medium with data concerning an astigmatic power        distribution, required for a full correction, for the        predetermined arrangement of the progressive power spectacle        lens in front of the eye of the progressive power spectacle        wearer, for whom the progressive power spectacle lens is        intended, and/or    -   (vii) a data medium with data concerning a prescription and an        object distance model for the predetermined arrangement of a        progressive power spectacle lens in front of the eye of a        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (viii) a data medium with data concerning a distribution of the        spherical equivalent for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, wherein        the progressive power spectacle lens has a distance portion and        a near portion, and the width of the intermediate corridor        corresponds to the dimension transverse to a longitudinal        direction of the intermediate corridor extending between the        distance portion and near portion, within which the absolute        value of the residual astigmatism lies below a predetermined        limit value, which is selected within a range from the group        specified below:    -   the limit value lies in the range between 0.25 dpt and 1.5 dpt,    -   the limit value lies in the range between 0.25 dpt and 1.0 dpt,    -   the limit value lies in the range between 0.25 dpt and 0.75 dpt,    -   the limit value lies in the range between 0.25 dpt and 0.6 dpt,    -   the limit value lies in the range between 0.25 dpt and 0.5 dpt,    -   the limit value is 0.5 dpt.

The above-described further exemplary embodiment of the product andoptionally its developments described above can be wherein the productfurthermore comprises (i) a representation, situated on a data medium,of a predetermined arrangement of the progressive power spectacle lensin front of an eye of a progressive power spectacle wearer, for whom theprogressive power spectacle lens is intended, or (ii) a data medium withdata concerning a predetermined arrangement of the progressive powerspectacle lens in front of an eye of a progressive power spectaclewearer, wherein

-   -   the progressive power spectacle lens has a distribution of a        spherical equivalent for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, in that    -   the product further comprises        -   (i) a representation, situated on a data medium, of a            residual astigmatism distribution for the predetermined            arrangement of the progressive power spectacle lens in front            of the eye of the progressive power spectacle wearer, for            whom the progressive power spectacle lens is intended,            and/or        -   (ii) a representation, situated on a data medium, of an            astigmatic power distribution, required for a full            correction, for the predetermined arrangement of the            progressive power spectacle lens in front of the eye of the            progressive power spectacle wearer, for whom the progressive            power spectacle lens is intended, and/or        -   (iii) a representation, situated on a data medium, of a            prescription and an object distance model for the            predetermined arrangement of the progressive power spectacle            lens in front of the eye of a progressive power spectacle            wearer, for whom the progressive power spectacle lens is            intended, and/or        -   (iv) a representation, situated on a data medium, of a            distribution of the spherical equivalent for the            predetermined arrangement of the progressive power spectacle            lens in front of the eye of the progressive power spectacle            wearer, for whom the progressive power spectacle lens is            intended, and/or        -   (v) a data medium with data concerning a residual            astigmatism distribution for the predetermined arrangement            of the progressive power spectacle lens in front of the eye            of the progressive power spectacle wearer, for whom the            progressive power spectacle lens is intended, and/or        -   (vi) a data medium with data concerning an astigmatic power            distribution, required for a full correction, for the            predetermined arrangement of the progressive power spectacle            lens in front of the eye of the progressive power spectacle            wearer, for whom the progressive power spectacle lens is            intended, and/or        -   (vii) a data medium with data concerning a prescription and            an object distance model for the predetermined arrangement            of the progressive power spectacle lens in front of the eye            of a progressive power spectacle wearer, for whom the            progressive power spectacle lens is intended, and/or        -   (viii) a data medium with data concerning a distribution of            the spherical equivalent for the predetermined arrangement            of the progressive power spectacle lens in front of the eye            of the progressive power spectacle wearer, for whom the            progressive power spectacle lens is intended, and in that

the refractive index of the progressive power spectacle lens varies inspace in such a way that the maximum value of the residual astigmatismof the progressive power spectacle lens is less than the maximum valueof the residual astigmatism of a comparison progressive power spectaclelens with the same distribution of the spherical equivalent in the caseof the same arrangement of the comparison progressive power spectaclelens in front of the eye of the progressive power spectacle wearer, butwith a spatially non-varying refractive index.

The above-described further exemplary embodiment of the product andoptionally its developments described above can also be wherein

the product furthermore comprises (i) a representation, situated on adata medium, of a predetermined arrangement of the progressive powerspectacle lens in front of an eye of a progressive power spectaclewearer, for whom the progressive power spectacle lens is intended, or(ii) a data medium with data concerning a predetermined arrangement ofthe progressive power spectacle lens in front of an eye of a progressivepower spectacle wearer, in that

the progressive power spectacle lens has a distribution of a sphericalequivalent (W) for the predetermined arrangement of the progressivepower spectacle lens in front of the eye of the progressive powerspectacle wearer, for whom the progressive power spectacle lens isintended, in that

the product further comprises

-   -   (i) a representation, situated on a data medium, of a residual        astigmatism distribution for the predetermined arrangement of        the progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (ii) a representation, situated on a data medium, of an        astigmatic power distribution, required for a full correction,        for the predetermined arrangement of the progressive power        spectacle lens in front of the eye of the progressive power        spectacle wearer, for whom the progressive power spectacle lens        is intended, and/or    -   (iii) a representation, situated on a data medium, of a        prescription and an object distance model for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of a progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (iv) a representation, situated on a data medium, of a        distribution of the spherical equivalent for the predetermined        arrangement of the progressive power spectacle lens in front of        the eye of the progressive power spectacle wearer, for whom the        progressive power spectacle lens is intended, and/or    -   (v) a data medium with data concerning a residual astigmatism        distribution for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (vi) a data medium with data concerning an astigmatic power        distribution, required for a full correction, for the        predetermined arrangement of the progressive power spectacle        lens in front of the eye of the progressive power spectacle        wearer, for whom the progressive power spectacle lens is        intended, and/or    -   (vii) a data medium with data concerning a prescription and an        object distance model for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of a        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and/or    -   (viii) a data medium with data concerning a distribution of the        spherical equivalent for the predetermined arrangement of the        progressive power spectacle lens in front of the eye of the        progressive power spectacle wearer, for whom the progressive        power spectacle lens is intended, and in that

the progressive power spectacle lens comprises an intermediate corridorand a principal line of sight, and in that the refractive index of theprogressive power spectacle lens varies in space in such a way that fora predetermined residual astigmatism value A_(Rest,Grenz) of the group

the residual astigmatism value A_(res,lim) lies in the range between0.25 dpt and 1.5 dpt,

the residual astigmatism value A_(res,lim) lies in the range between0.25 dpt and 1.0 dpt,

the residual astigmatism value A_(res,lim) lies in the range between0.25 dpt and 0.75 dpt,

the residual astigmatism value A_(res,lim) lies in the range between0.25 dpt and 0.6 dpt,

the residual astigmatism value A_(res,lim) lies in the range between0.25 dpt and 0.5 dpt,

the residual astigmatism value A_(res,lim) is 0.5 dpt,

on a horizontal section at the narrowest point of the intermediatecorridor or for a horizontal section through the point on the principalline of sight at which the half addition is achieved, the followingrelationship applies within a region with a horizontal distance of 10 mmon both sides of the principal line of sight:

$B > {c \times \frac{A_{{res},\lim}}{{grad}\mspace{14mu} W}}$

where grad W describes the power gradient of the spherical equivalent ofthe progressive power spectacle lens at the narrowest point of theintermediate corridor on the principal line of sight or in a point onthe principal line of sight at which the half addition is achieved, Bdescribes the width of the region in the progressive power spectaclelens in which the residual astigmatism is A_(res)≤A_(res,lim), where cis a constant selected from the group:

-   -   (b) 1.0<c    -   (c) 1.1<c    -   (d) 1.2<c    -   (e) 1.3<c.

There are statements above to the effect of the inventors havingrecognized that the interplay of the degree of complexity of thegeometry of the progressive surface and the degree of the complexity ofthe refractive index distribution is decisive. Thus, deviating from thesolution described in WO 89/04986 A1, they propose acomputer-implemented method, in the form of a ray tracing method, fordesigning a progressive power spectacle lens having a front surface anda back surface and a spatially varying refractive index, in which eitherthe front surface or the back surface or both surfaces are embodied asprogressive surfaces. Optical properties of the progressive powerspectacle lens are calculated by means of the ray tracing method at aplurality of evaluation points, at which visual rays pass through theprogressive power spectacle lens. In this ray tracing method, at leastone intended optical property for the progressive power spectacle lensis set at the respective evaluation point. Initially, a design for theprogressive power spectacle lens is set, wherein this design comprises arepresentation of a local surface geometry of the progressive surfaceand a local refractive index of the progressive power spectacle lens inthe respective visual beam path through the evaluation points. Thedesign of the progressive power spectacle lens is modified in view of anapproximation of the at least one intended optical property of theprogressive power spectacle lens. According to the disclosure, themodifying comprises not only modifying the representation of the localsurface geometry of the progressive surface but also modifying the localrefractive index of the progressive power spectacle lens in therespective visual beam path through the evaluation points, wherein theat least one intended optical property comprises an intended residualastigmatism of the progressive power spectacle lens.

As a rule, the surface lying opposite the modified progressive surfaceis fixedly prescribed. In general, the former comprises a simple surfacegeometry, such as, e.g., a spherical, rotationally symmetric asphericalor toric geometry. In the case of a toric surface, the surface geometryand axis position are frequently chosen in such a way that (apart froman unwanted residual astigmatism) they compensate the astigmaticrefraction deficit of the eye of the progressive power spectacle wearer.The surface lying opposite the modified progressive surface can also bea progressive surface, optionally a freeform surface, too, with afixedly prescribed surface geometry. The former surface can contributeto the increase in power required for providing the addition. Themodified progressive surface, too, can contribute to the increase inpower required for providing the addition. It is also possible for bothsurfaces, specifically the front surface and back surface, to bemodified together with the refractive index distribution for thepurposes of approximating the intended residual astigmatismdistribution.

Ray tracing methods for use when designing progressive power spectaclelenses are known. In particular, reference is made to Werner Köppen:Konzeption and Entwicklung von Progressivgläsern, in Deutsche OptikerZeitung DOZ 10/95, pages 42-46 as well as EP 2 115 527 B1 and thedocuments specified therein. The calculation of optimized spatiallydependent refractive index distributions by means of optical computingprograms, for example the computing program ZEMAX by Zemax, LLC, islikewise known. By way of example, reference is made to the ZEMAXInternet presence at www.zemax.com.

Setting intended properties for a spectacle lens relates to theso-called design of a spectacle lens. A design of a spectacle lensusually comprises the distribution of the intended values for one ormore imaging aberrations, which typically are included in theoptimization of the spectacle lens as target values or when determiningthe target values. In particular, a spectacle lens design ischaracterized by the distribution of the refractive error (i.e., thedifference between the spherical equivalent of the progressive powerspectacle lens in the beam path in the use position and the sphericalequivalent ascertained by determining refraction) and/or thedistribution of the residual astigmatism (i.e., the difference betweenthe astigmatism of the spectacle lens and the astigmatism which isascertained by determining the refraction). Instead of the term residualastigmatism distribution, the literature also uses the terms astigmaticaberration distribution and astigmatic deviation. Further, a spectaclelens design may likewise comprise the distribution of the intendedvalues for magnification, distortion or other imaging aberrations, moreparticularly higher order imaging aberrations, as described in EP 2 115527 B1. Here, these may relate to surface values or, typically, usevalues, i.e., values in the use position of the spectacle lens.

According to the disclosure, the design of the progressive powerspectacle lens is modified with the target of coming as close aspossible to the predetermined intended residual astigmatism. By way ofexample, the intended residual astigmatism can be set to be zero at allevaluation points. It is also possible to predetermine a residualastigmatism distribution that typically has far smaller values thanthose that are theoretically achievable at all by means of aconventional progressive power spectacle lens with a spatiallynon-varying refractive index but freeformed back surface (and/or frontsurface) or that are predetermined for the optimization of such aprogressive power spectacle lens. The number of evaluation points,according to Werner Köppen: Konzeption and Entwicklung vonProgressivgläsern, in Deutsche Optiker Zeitung DOZ 10/95, pages 42-46,typically lies in the range between 1000 and 1500. EP 2 115 527 B1proposes that the evaluation points number more than 8000.

In order to come as close as possible to this target, it is, accordingto the disclosure, not only the surface geometry of the (subsequent)progressive surface that is locally modified at the evaluation point,but also the local refractive index in the medium of the progressivepower spectacle lens, passed by the beam path, at the evaluation point.The term medium is understood to mean the material or materials thatmake up the progressive power spectacle lens.

According to the disclosure, the progressive surface is modified freelyin two spatial dimensions and the local refractive index is alsomodified freely in at least two spatial dimensions.

In order to come as close to the target as possible, this procedure ofmodifying must, as a rule, be carried out multiple times, i.e.,iteratively. Here, it should once again be clarified that both the localsurface geometry and the local refractive index can vary freely andneither the local surface geometry nor the local refractive index isfixed during the modification, in particular during the iteration. Bycontrast, WO 89/04986 A1 teaches the prescription of comparativelysimple geometries for the front and back surface and the search for asuitable refractive index distribution in order to establish the powerincrease necessary for providing the addition and, optionally, in orderto wholly or partly rectify the (residual) astigmatism along theprincipal line of sight and further undertake corrections of imagingaberrations to the side of the principal meridian where necessary.

Even though, as a rule, the refractive index is wavelength-dependent,dispersion is generally not taken into account and the calculation isimplemented for a so-called design wavelength. However, an optimizationprocess taking account of different design wavelengths, as described inEP 2 383 603 B1, for example, is not precluded.

Since the modification is carried out with the target of coming as closeas possible to intended optical properties, a person skilled in the artalso talks about an optimization. The modification is carried out untila termination criterion is satisfied. In the ideal case, the terminationcriterion consists of the designed progressive power spectacle lenshaving the predetermined intended optical properties. In the case wherethe residual astigmatism is set to be zero at all evaluation points,this ideal case would be that the residual astigmatism of the calculatedspectacle lens is in fact zero at all evaluation points. However, sincethis will regularly not be the case, particularly in the described case,there is a termination of the calculation, e.g., after reaching one ormore limit values in the surroundings of the intended property(properties) or after reaching a predetermined number of iterations.

Usually, the ascertainment of the intended properties and thecalculation of the actual properties is based on model calculations thattake account of the use conditions, specifically, e.g., the seat of thespectacle lenses in front of the eye and an object distance model, andphysiological parameters of the spectacle wearer, specifically, e.g.,the refractive error, the accommodation capability and the pupillarydistance. Details have already been described above.

As a rule, the result of the approximation of the at least one intendedoptical property (properties) of the progressive power spectacle lens bymodifying the local refractive index and the local surface geometry isthat the front surface embodied as a progressive surface is embodied asa freeform surface and/or that the back surface embodied as aprogressive surface is embodied as a freeform surface.

The object stated at the outset is achieved in its entirety by themethod according to the disclosure described above.

In one advantageous configuration of the method according to thedisclosure, the progressive surface is modified in such a way that afreeform surface arises which has neither a point symmetry nor an axialsymmetry. Modifying the local refractive index is furthermore effectedin such a way that

-   -   (a) the refractive index varies only in a first spatial        dimension and in a second spatial dimension and is constant in a        third spatial dimension, such that a distribution of the        refractive index in the first spatial dimension and the second        spatial dimension has neither point symmetry nor axial symmetry,        or    -   (b) the refractive index varies in a first spatial dimension and        in a second spatial dimension and in a third spatial dimension,        such that a distribution of the refractive index in the first        spatial dimension and the second spatial dimension in all planes        perpendicular to the third spatial dimension has neither point        symmetry nor axial symmetry, or    -   (c) the refractive index varies in a first spatial dimension and        in a second spatial dimension and in a third spatial dimension,        such that a distribution of the refractive index in the        progressive power spectacle lens has no point symmetry and no        axial symmetry at all.

The aim of the disclosure is to reduce the residual astigmaticaberrations and optionally also the residual spherical aberrations,alongside the principal line of sight (i.e. in the central region of theintermediate portion). Proceeding from (i) a design of a conventionalprogressive power spectacle lens with a spatially constant refractiveindex or (ii) a target design for a conventional progressive powerspectacle lens with a spatially constant refractive index (that is tosay the target design that was used for the optimization of theprogressive power spectacle lens with a constant refractive index), anew target design for a progressive power spectacle lens with aspatially varying refractive index can be produced which contains theprevious distribution of the residual spherical and astigmaticaberrations, but the latter are reduced especially in the centralintermediate portion. In this case, the residual astigmatic aberrationsare typically reduced in a region around the principal line of sight(e.g. the region at a distance of 5, 10 to 20 mm from the principal lineof sight), e.g. by their being multiplied by a factor of 0.5 to 0.8, inorder to attain an improved target design.

One embodiment exemplary embodiment of this method according to thedisclosure is wherein the modification of the design of the progressivepower spectacle lens is implemented in view of a minimization of atarget function. Such a target function is also referred to as“Kostenfunktion” [“cost function”] in the German literature and as meritfunction in the English literature. When designing progressive powerspectacle lenses, the method of least squares is very frequently appliedas a method for minimizing a target function, as practiced, for example,in EP 0 857 993 B2, EP 2 115 527 B1 or else Werner Köppen: Konzeptionand Entwicklung von Progressivgläsern, in Deutsche Optiker Zeitung DOZ10/95, pages 42-46. The embodiment exemplary embodiment according to thedisclosure applies this method with the target function reproducedbelow:

F=Σ _(m) P _(m)Σ_(n) W _(n)(T _(n) −A _(n))².

In this target function F, P_(m) is the weighting at the evaluationpoint m, W_(n) is the weighting of the optical property n, T_(n) is theintended value of the optical property n at the respective evaluationpoint m and A_(n) is the actual value of the optical property n at theevaluation point m.

The application of this method has proven to be worthwhile for designingconventional type progressive power spectacle lenses. The disclosureproposes to also use this method for designing gradient index (GRIN)progressive power spectacle lenses according to the disclosure.

The target design can e.g. also be fixed by the stipulation of residualoptical, in particular spherical and astigmatic, aberrations at manypoints distributed over the front surface of the entire lens.

In this case, there may be specifications for the distances of theobjects for which the powers and/or residual spherical and astigmaticaberrations for the spectacle wearer when looking through the spectaclelens are determined.

Furthermore, there may be stipulations for the surface curvatures atfurther points on the progressive surface, thickness requirements (inparticular in the geometric center and at the edge of the progressivepower spectacle lens) and prismatic requirements at further points.

An individual weighting can be assigned to each of these optical andgeometric stipulations at each of the aforementioned points. If theresidual aberrations, surface curvatures, prismatic powers andthicknesses for the stipulation at the point are determined for astarting lens (e.g. the progressive power spectacle lens optimized forthe constant refractive index), it is thus possible to determine a totalaberration F according to what has been indicated above. This functionvalue F dependent on the optical and geometric lens properties can beminimized by means of known mathematical methods by simultaneouslychanging the surface geometry and the refractive index distribution. Aprogressive power spectacle lens having improved properties in regard tothe requirements specified above is obtained in this way.

Alternatively, for the optimization of the progressive power spectaclelens with a material with the variable refractive index, it is alsopossible to use the original target design, that is to say the targetdesign that was used for the optimization of the lens with a constantrefractive index.

In this case, the weightings used in the optimization with the originaldesign can be used or else altered. In particular, the weighting for theresidual astigmatic and spherical aberrations in the intermediatecorridor can be increased in order to obtain improved properties of theprogressive power spectacle lens in the progression region.

However, increasing the weighting in the intermediate corridor isexpedient here only if the astigmatic and spherical aberrations of theoptimized lens with a material with a constant refractive index do notalready correspond to the stipulations of the (new) target design.

If the original design had already been accepted by the spectaclewearer, this procedure yields at any rate a more compatible design forthe spectacle wearer since the residual optical aberrations are reducedwith the new design.

What is achieved overall is a new improved target design which is notachievable with a material with a constant refractive index, but withthis target design and by means of simultaneous optimization of the formof the freeform surfaces and the distribution of the refractive indexfor a material with a non-constant refractive index, it is possible toachieve an improved progressive power spectacle lens design having, inparticular, a wider intermediate corridor, lower maximum residualastigmatic aberrations in the intermediate region and thus also lessdistortion in the intermediate region.

This new progressive power spectacle lens design can be realized heretaking account of the original conditions of use, thicknessstipulations, etc.

One particularly advantageous embodiment exemplary embodiment of themethod according to the disclosure is wherein an intended residualastigmatism is predetermined for at least one evaluation point, theintended residual astigmatism being less than the smallest theoreticallyachievable residual astigmatism at the at least one correspondingevaluation point on a comparison progressive power spectacle lens, forthe same prescription and the same object distance model, but with thesame distribution of the spherical equivalent and the same arrangementof the comparison progressive power spectacle lens in front of the eyeof the progressive power spectacle wearer, but with a spatiallynon-variable refractive index, and in that modifying the representationof the local surface geometry of the progressive surface and of thelocal refractive index of the progressive power spectacle lens in therespective visual beam path through the evaluation points is onlyterminated if the residual astigmatism at the at least one evaluationpoint, achieved for the planned progressive power spectacle lens, isless than the theoretically achievable residual astigmatism at the atleast one corresponding evaluation point on the comparison progressivepower spectacle lens.

It is possible—as already explained above—to set the intended residualastigmatism to be zero at all evaluation points. In order to plan aprogressive power spectacle lens that, over the entire surface, hasbetter optical properties than a conventional comparison progressivepower spectacle lens, the intended residual astigmatism at allevaluation points will be chosen to be lower, at least by a significantpercentage of, e.g., 10-50%, than what is usually set when planning thecomparison progressive power spectacle lens. In general, at least at theevaluation points, an intended residual astigmatism will bepredetermined that is less than the theoretically achievable residualastigmatism at the at least corresponding evaluation points in thecomparison progressive power spectacle lens that should lie within thesubsequent intermediate corridor. This is because a broadening of theintermediate corridor is always desirable.

As an alternative or in addition to the advantageous embodimentexemplary embodiment described above, one method exemplary embodimentconsists in carrying out a modification of the representation of thelocal surface geometry of the progressive power surface and of the localrefractive index of the progressive power spectacle lens in therespective visual beam path through the evaluation points with thestipulation that the maximum value of the residual astigmatism of theprogressive power spectacle lens is less than the maximum value of theresidual astigmatism of a comparison progressive power spectacle lens,for the same prescription, with the same distribution of the sphericalequivalent and the same arrangement of the comparison progressive powerspectacle lens in front of the eye of the progressive power spectaclewearer, but with a spatially non-variable refractive index. Inprinciple, the maximum value for the residual astigmatism in theprogressive power spectacle lens planned according to the disclosureneed not be placed at the “same” location or the “same” evaluation pointas the maximum value for the residual astigmatism in the comparisonprogressive power spectacle lens. However, this may also be consideredas a constraint when carrying out the method. As a result of theseprescriptions, the optical properties of the progressive power spectaclelens according to the disclosure are further improved in relation to acomparison progressive power spectacle lens that was manufactured in aconventional way.

In one embodiment exemplary embodiment, the method according to thedisclosure can be carried out in such a way that, when planning theprogressive power spectacle lens, a progressive power spectacle lenscorresponding to a product of the above-described types arises. Theadvantages of these products were already described in detail above.

In a further method exemplary embodiment according to the disclosure,provision is even made for the progressive power spectacle lens to beplanned precisely with the stipulation of producing a progressive powerspectacle lens according to a product according to any one of the typesdescribed above. The intended properties and the termination conditionsin this further exemplary embodiment are chosen in such a way that thecorresponding progressive power spectacle lens with the above-describedoptical properties necessarily arises in the arrangement in front of theeye of the future spectacle wearer, as predetermined by therepresentation, when carrying out planning.

Further, the disclosure provides a computer program with program codefor carrying out all of the process steps according to any one of theabove-described methods when the computer program is loaded onto acomputer and/or run on a computer. The computer program can be saved onany non-transient computer-readable medium, in particular on a hard diskdrive of a computer, on a USB stick, or else in the cloud.

Accordingly, the disclosure also seeks protection for acomputer-readable medium with a computer program of the type describedabove.

The disclosure also relates to a method for producing, by way of anadditive method, a progressive power spectacle lens according to any oneof the products described above or a progressive power spectacle lensplanned using a method of the above-described exemplary embodiments.

Additive methods are methods in which the progressive power spectaclelens is constructed sequentially. Particularly in this context, it isknown that so-called digital fabricators, in particular, offermanufacturing options for virtually any structure, the structures notbeing realizable or only being realizable with difficulty usingconventional abrasive methods. Within the digital fabricator machineclass, 3D printers represent the most important subclass of additive,i.e., accumulating, building fabricators. The most important techniquesof 3D printing are selective laser melting (SLM) and electron-beammelting for metals and selective laser sintering (SLS) for polymers,ceramics and metals, stereolithography (SLA) and digital lightprocessing for liquid artificial resins and multijet or polyjet modeling(e.g., inkjet printers) and fused deposition modeling (FDM) for plasticsand, in part, artificial resins. Further, construction with the aid ofnanolayers is also known, as described, for example, atpeaknano.com/wp-content/uploads/PEAK-1510-GRINOptics-Overview.pdf,retrieved on Jan. 12, 2017.

Source materials for manufacturing by means of 3D printing and optionsfor the 3D manufacturing method itself can be gathered from, forexample, the European patent application EP3312661.

A development of the disclosure consists in a method for producing aprogressive power spectacle lens comprising a method for planning aprogressive power spectacle lens as described above and manufacturingthe progressive power spectacle lens according to the plan.

Manufacturing the progressive power spectacle lens according to the plancan, according to the disclosure, once again be implemented by anadditive method.

Another development of the disclosure consists in a computer comprisinga processor configured to carry out a method for planning a progressivepower spectacle lens according to any one of the above-described typesor exemplary embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will now be described with reference to the drawingswherein:

FIG. 1A shows the mean spherical power of a comparison progressive powerspectacle lens of conventional construction made of a material with arefractive index of n=1.600 in relation to a GRIN progressive powerspectacle lens with a vertical plane of symmetry according to a firstexemplary embodiment of the disclosure;

FIG. 1B shows the mean surface optical power of the comparisonprogressive power spectacle lens, object-side freeform surface of FIG.1A;

FIG. 1C shows the surface astigmatism of the object-side freeformsurface of the comparison progressive power spectacle lens of FIG. 1A;

FIG. 2A shows the mean spherical power of the GRIN progressive powerspectacle lens according to the first exemplary embodiment;

FIG. 2B shows the mean surface optical power, calculated for a constantrefractive index of n=1.600 for the object-side freeform surface, of theGRIN progressive power spectacle lens of FIG. 2A;

FIG. 2C shows the surface astigmatism for n=1.600 of the object-sidefreeform surface of the GRIN progressive power spectacle lens of FIG.2A;

FIG. 3 shows the distribution of the refractive index of the GRINprogressive power spectacle lens according to the first exemplaryembodiment;

FIG. 4A shows the residual astigmatism distribution of the comparisonprogressive power spectacle lens;

FIG. 4B shows the residual astigmatism distribution of the GRINprogressive power spectacle lens according to the disclosure accordingto the first exemplary embodiment;

FIGS. 5A and 5B show a comparison of the residual astigmatism profile ofthe GRIN progressive power spectacle lens according to the firstexemplary embodiment with the residual astigmatism profile of thecomparison progressive power spectacle lens along a section at y=0according to FIGS. 4A and 4B, respectively;

FIG. 5A shows the residual astigmatism profile of the comparisonprogressive power spectacle lens according to FIG. 4A;

FIG. 5B shows residual astigmatism profile of the GRIN progressive powerspectacle lens according to FIG. 4B;

FIGS. 6A and 6B show a comparison of the contour of the front surface ofthe GRIN progressive power spectacle lens according to the firstexemplary embodiment with the contour of the front surface of thecomparison progressive power spectacle lens;

FIG. 6A shows the sagittal heights of the front surface of thecomparison progressive power spectacle lens according to FIG. 4A;

FIG. 6B shows the sagittal heights of the front surface of the GRINprogressive power spectacle lens according to FIG. 4B;

FIG. 7A shows the mean spherical power of a comparison progressive powerspectacle lens of conventional construction made of a material with arefractive index of n=1.600 in relation to a GRIN progressive powerspectacle lens with a vertical plane of symmetry according to a secondexemplary embodiment of the disclosure;

FIG. 7B shows the mean surface optical power, object-side freeformsurface, of the comparison progressive power spectacle lens according toFIG. 7A;

FIG. 7C shows the surface astigmatism of the object-side freeformsurface of the comparison progressive power spectacle lens of FIG. 7A;

FIG. 8A shows the mean spherical power of the GRIN progressive powerspectacle lens according to the second exemplary embodiment;

FIG. 8B shows the mean surface optical power, calculated for arefractive index of n=1.600 for the object-side surface of theprogressive power spectacle lens according to FIG. 8A;

FIG. 8C shows the surface astigmatism for n=1.600 of the object-sidefreeform surface of the progressive power spectacle lens according toFIG. 8A;

FIG. 9 shows the distribution of the refractive index of the GRINprogressive power spectacle lens according to the second exemplaryembodiment;

FIGS. 10A and 10B show a comparison of the residual astigmatismdistribution of the GRIN progressive power spectacle lens according tothe second exemplary embodiment with the residual astigmatismdistribution of the comparison progressive power spectacle lens;

FIG. 10A shows the residual astigmatism distribution of the comparisonprogressive power spectacle lens;

FIG. 10 B shows the residual astigmatism distribution of the GRINprogressive power spectacle lens according to the disclosure accordingto the second exemplary embodiment;

FIGS. 11A and 11B show a comparison of the residual astigmatism profileof the GRIN progressive power spectacle lens according to the secondexemplary embodiment with the residual astigmatism profile of thecomparison progressive power spectacle lens along a section at y=−5 mmaccording to FIGS. 10A and 10B, respectively;

FIG. 11A shows the residual astigmatism profile of the comparisonprogressive power spectacle lens according to FIG. 10A;

FIG. 11B shows the residual astigmatism profile of the GRIN progressivepower spectacle lens according to the disclosure according to FIG. 10B;

FIGS. 12A and 12B show a comparison of the contour of the front surfaceof the GRIN progressive power spectacle lens according to the secondexemplary embodiment with the contour of the front surface of thecomparison progressive power spectacle lens; the sagittal heights arespecified in relation to a plane tilted through −7.02° about thehorizontal axis;

FIG. 12A shows the sagittal heights of the front surface of thecomparison progressive power spectacle lens;

FIG. 12B shows the sagittal heights of the front surface of the GRINprogressive power spectacle lens according to the disclosure accordingto the second exemplary embodiment;

FIGS. 13A to 13C show optical properties of a comparison progressivepower spectacle lens of conventional construction made of a materialwith a refractive index of n=1.600 in relation to a GRIN progressivepower spectacle lens without any symmetry according to a third exemplaryembodiment of the disclosure;

FIG. 13A shows the mean spherical power of the comparison progressivepower spectacle lens;

FIG. 13B shows the mean surface optical power of the comparisonprogressive power spectacle lens, object-side freeform surface, of thecomparison progressive power spectacle lens of FIG. 13A;

FIG. 13C shows the surface astigmatism of the object-side freeformsurface of the comparison progressive power spectacle lens of FIG. 13A;

FIG. 14A shows the mean spherical power of the GRIN progressive powerspectacle lens according to the third exemplary embodiment;

FIG. 14B shows the mean surface optical power of the object-sidefreeform surface, calculated for a refractive index of n=1.600, of theprogressive power spectacle lens according to FIG. 14A;

FIG. 14C shows the surface astigmatism for n=1.600 of the object-sidefreeform surface of the GRIN progressive power spectacle lens of FIG.14A;

FIG. 15 shows the distribution of the refractive index of the GRINprogressive power spectacle lens according to the third exemplaryembodiment;

FIGS. 16A and 16B show a comparison of the residual astigmatismdistribution of the GRIN progressive power spectacle lens according tothe third exemplary embodiment with the residual astigmatismdistribution of the comparison progressive power spectacle lens;

FIG. 16A shows the residual astigmatism distribution of the comparisonprogressive power spectacle lens;

FIG. 16B shows the residual astigmatism distribution of the GRINprogressive power spectacle lens according to the disclosure accordingto the third exemplary embodiment;

FIGS. 17A and 17B show a comparison of the residual astigmatism profileof the GRIN progressive power spectacle lens according to the thirdexemplary embodiment with the residual astigmatism profile of thecomparison progressive power spectacle lens along a section at y=−5 mmaccording to FIGS. 16A and 16B, respectively;

FIG. 17A shows the residual astigmatism profile of the comparisonprogressive power spectacle lens;

FIG. 17B shows the residual astigmatism profile of the GRIN progressivepower spectacle lens according to the disclosure according to the thirdexemplary embodiment;

FIGS. 18A-1 and 18A-2 and FIGS. 18B1 and 18B-2 show a comparison of thecontour of the front surface of the GRIN progressive power spectaclelens according to the third exemplary embodiment with the contour of thefront surface of the comparison progressive power spectacle lens;

FIGS. 18A-1 and 18A-2 show the sagittal heights of the front surface ofthe comparison progressive power spectacle lens;

FIGS. 18B-1 and 18B-2 show the sagittal heights of the front surface ofthe GRIN progressive power spectacle lens according to the disclosureaccording to the third exemplary embodiment;

FIG. 19A shows the mean spherical power of the comparison progressivepower spectacle lens of a comparison progressive power spectacle lens ofconventional construction made of a material with a refractive index ofn=1.600 in relation to a GRIN progressive power spectacle lens withoutany symmetry according to a fourth exemplary embodiment according to thedisclosure;

FIG. 19B shows the mean surface optical power of the comparisonprogressive power spectacle lens, eye-side freeform surface of thecomparison progressive power spectacle lens of FIG. 19A;

FIG. 19C shows the surface astigmatism of the eye-side freeform surfaceof the comparison progressive power spectacle lens of FIG. 19A;

FIG. 20A shows the mean spherical power of the GRIN progressive powerspectacle lens according to the fourth exemplary embodiment;

FIG. 20B shows the mean surface optical power of the eye-side freeformsurface, calculated for a refractive index of n=1.600 of the GRINprogressive power spectacle lens according to FIG. 20A;

FIG. 20C shows the surface astigmatism for n=1.600 of the eye-sidefreeform surface of the GRIN progressive power spectacle lens of FIG.20A;

FIG. 21 shows the distribution of the refractive index of the GRINprogressive power spectacle lens according to the fourth exemplaryembodiment;

FIGS. 22A and 22B show a comparison of the residual astigmatismdistribution of the GRIN progressive power spectacle lens according tothe fourth exemplary embodiment with the residual astigmatismdistribution of the comparison progressive power spectacle lens;

FIG. 22A shows the residual astigmatism distribution of the comparisonprogressive power spectacle lens;

FIG. 22B shows the residual astigmatism distribution of the GRINprogressive power spectacle lens according to the disclosure accordingto the fourth exemplary embodiment;

FIGS. 23A and 23B show a comparison of the residual astigmatism profileof the GRIN progressive power spectacle lens according to the fourthexemplary embodiment with the residual astigmatism profile of thecomparison progressive power spectacle lens along a section at y=−4 mmaccording to FIGS. 22A and 22B, respectively;

FIG. 23A shows the residual astigmatism profile of the comparisonprogressive power spectacle lens;

FIG. 23B shows the residual astigmatism profile of the GRIN progressivepower spectacle lens according to the disclosure according to the fourthexemplary embodiment;

FIGS. 24A-1 and 24A-2 and FIGS. 24B-1 and 24B-2 show a comparison of thecontour of the back surface of the GRIN progressive power spectacle lensaccording to the fourth exemplary embodiment with the contour of theback surface of the comparison progressive power spectacle lens;

FIGS. 24A-1 and 24A-2 show the sagittal heights of the back surface ofthe comparison progressive power spectacle lens;

FIGS. 24B-1 and 24B-2 show the sagittal heights of the back surface ofthe GRIN progressive power spectacle lens according to the disclosureaccording to the fourth exemplary embodiment;

FIG. 25A shows the mean spherical power of the GRIN progressive powerspectacle lens without any symmetry according to the fifth exemplaryembodiment, designed for the prescription values sphere −4 dpt, cylinder2 dpt, axis 90 degrees;

FIG. 25B shows the mean surface optical power of the eye-side freeformsurface, calculated for a refractive index of n=1.600 of the GRINprogressive power spectacle lens according to FIG. 25A;

FIG. 25C shows the surface astigmatism for n=1.600 of the eye-sidefreeform surface of the GRIN progressive power spectacle lens of FIG.25A;

FIG. 26 shows the distribution of the refractive index of the GRINprogressive power spectacle lens according to the fifth exemplaryembodiment;

FIG. 27A shows residual astigmatism of the GRIN progressive powerspectacle lens according to the fifth exemplary embodiment;

FIG. 27A shows residual astigmatism of the GRIN progressive powerspectacle lens according to the fifth exemplary embodiment;

FIG. 27B shows the residual astigmatism profile along a section at y=−4mm of the GRIN progressive power spectacle lens according to thedisclosure according to the fifth exemplary embodiment; and

FIGS. 28A-1 and 28A-2 shows sagittal heights of the back surface of theGRIN progressive power spectacle lens according to the disclosureaccording to the fifth exemplary embodiment.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

The first five exemplary embodiments relate to GRIN progressive powerspectacle lenses or the representation thereof in a memory of a computeraccording to a product of the type according to the disclosure. Thesixth exemplary embodiment shows, in exemplary fashion, a methodaccording to the disclosure for planning a GRIN progressive powerspectacle lens.

First Exemplary Embodiment

A progressive power spectacle lens with a particularly simple surfacegeometry is chosen in the first example. It is constructed in mirrorsymmetric fashion in relation to a plane perpendicular to the plane ofthe drawing and substantially only consists of a zone with continuouslyincreasing power that is arranged in a central region and extendsperpendicularly from top to bottom.

FIG. 1A shows the distribution of the mean spherical power in the beampath for the spectacle wearer for a progressive power spectacle lensmade of a standard material (refractive index n=1.600) with anobject-side freeform surface, which is described by so-called bicubicsplines. This progressive power spectacle lens serves as a comparisonprogressive power spectacle lens for a progressive power spectacle lensembodied according to the disclosure, which is referred to below as aGRIN progressive power spectacle lens on account of its spatiallyvarying refractive index.

The back side of the comparison progressive power spectacle lens is aspherical surface with a radius of 120 mm and the center of rotation ofthe eye lies behind the geometric center of the lens at a distance of25.5 mm from the back surface. The lens has a central thickness of 2.5mm and a prismatic power of 0 at the geometric center. The back surfaceis untilted, i.e., both front surface and back surface have a normal inthe direction of the horizontally straight-ahead direction of view atthe geometric center.

The plotted coordinate axes x and y serve to determine points on thissurface. On the perpendicular central axis of the lens, the powerexceeds the 0.00 diopter at a height of approximately y=25 mm; a powerof 2.25 dpt (diopter) is reached at approximately y=−25 mm. Accordingly,the lens power increases by 2.25 diopter along this length of 50 mm.Accordingly, the progressive power spectacle lens has no spherical power(sphere=0) and no astigmatic power (cylinder=0) in the distance portionand an addition of 2.25 dpt for the spectacle wearer in the intended useposition. According to section 11.1 of DIN EN ISO 13666:2013-10, aspectacle lens with spherical power is a lens which brings a paraxialpencil of parallel light to a single focus. According to section 12.1 ofDIN EN ISO 13666:2013-10, a spectacle lens with astigmatic power is alens bringing a paraxial pencil of parallel light to two separate linefoci mutually at right angles and hence having vertex power in only thetwo principal meridians. Section 14.2.1 of this standard defines theaddition as difference between the vertex power of the near portion andthe vertex power of the distance portion.

FIG. 1B shows the mean surface optical power for n=1.600 of theobject-side freeform surface of the comparison progressive powerspectacle lens of FIG. 1A. The surface curvature increases continuouslyfrom top to bottom; the mean surface power value increases fromapproximately 5.3 dpt at y=15 mm to approximately 7.0 dpt at y=−25 mm.

FIG. 1C shows the surface astigmatism for n=1.600 of the object-sidefreeform surface of the comparison progressive power spectacle lens ofFIG. 1A.

FIGS. 2A, 2B, and 2C show the reproduction of the comparison progressivepower spectacle lens using a GRIN material. In this respect, FIG. 2Ashows the distribution of the mean spherical power. From the comparisonof FIG. 1A and FIG. 2A, it is possible to gather that the powerdistribution of the two progressive power spectacle lenses is the same.FIG. 2B illustrates the profile of the mean surface optical power andFIG. 2C illustrates the profile of the surface astigmatism of the frontsurface of the GRIN progressive power spectacle lens embodied accordingto the disclosure. In order to allow a comparison with FIG. 1B inrespect of the mean curvatures and with FIG. 1C in respect of thesurface astigmatism, it was not the GRIN material that was used whencalculating the mean surface optical power and the surface astigmatismbut, like previously, the material with the refractive index of n=1.600.

The mean surface optical power and the surface astigmatism are definedaccording to Heinz Diepes, Ralf Blendowske: Optik and Technik derBrille; 2nd edition, Heidelberg 2005, page 256.

The comparison of FIGS. 2B and 2C with FIGS. 1B and 1C shows that theform of the freeform surface has changed significantly: The mean surfaceoptical power (calculated with n=1.600) now decreases from top tobottom, i.e., the mean curvature of the surface reduces from top tobottom. The profile of the surface astigmatism no longer exhibits atypical intermediate corridor.

FIG. 3 shows the distribution of the refractive index over the GRINprogressive power spectacle lens according to the disclosure. Here, therefractive index increases from top to bottom from approximately n=1.48to approximately n=1.75 in the lower region.

FIGS. 4A and 4B show a comparison of the residual astigmatismdistribution of the GRIN progressive power spectacle lens according tothe first exemplary embodiment with the residual astigmatismdistribution of the comparison progressive power spectacle lens. FIG. 4Aand FIG. 4B represent the effects of using the GRIN material with itsspecific refractive index distribution and of the design of the freeformsurface for this GRIN progressive power spectacle lens on the width ofthe intermediate corridor in comparison with the standard lens. FIGS. 4Aand 4B show the distribution of the residual astigmatic aberration inthe beam path for the spectacle wearer, for a spectacle wearer with onlya prescription for sphere.

In this exemplary embodiment, the intermediate corridor, defined here bythe isoastigmatism line of 1 dpt, is widened from 17 mm to 22 mm, i.e.,by approximately 30 percent.

FIG. 5A and FIG. 5B show cross sections through the residual astigmatismdistributions from FIG. 4A and FIG. 4B. Here, the conventionalrelationship between increasing power and the lateral increase in theastigmatic aberration induced thereby (similar to the relationship ofthe mean surface optical power to the surface astigmatism according toMinkwitz's theorem) becomes particularly clear. The increase of theastigmatism in the surroundings of the center of the intermediatecorridor (y=0) is significantly lower for the GRIN lens, even though thesame power increase is present as in the standard lens. Precisely thisincrease is explained by Minkwitz's statement in the theory of optics ofprogressive power lenses.

FIGS. 6A and 6B compare the contour of the front surface of the GRINprogressive power spectacle lens according to the first exemplaryembodiment with the contour of the front surface of the comparisonprogressive power spectacle lens with the aid of a sagittal heightrepresentation. FIG. 6B shows the sagittal heights of the front surfaceof the GRIN progressive power spectacle lens according to the disclosureaccording to the first exemplary embodiment and, in comparisontherewith, FIG. 6A shows the sagittal heights of the front surface ofthe comparison progressive power spectacle lens.

Second Exemplary Embodiment

All of the following drawings correspond in subject matter and sequenceto those of the first exemplary embodiment.

FIG. 7A shows the distribution of the mean spherical power in the beampath for the progressive power spectacle wearer for a comparisonprogressive power spectacle lens made of a standard material (refractiveindex n=1.600) with an object-side freeform surface. The back side is,again, a spherical surface with a radius of 120 mm and the center ofrotation of the eye lies 4 mm above the geometric center of thecomparison progressive power spectacle lens at a horizontal distance of25.8 mm from the back surface. The comparison progressive powerspectacle lens has a central thickness of 2.6 mm and a prismatic power1.0 cm/m base 270°, 2 mm below the geometric center. The back surface istilted through −8° about the horizontal axis.

The plotted coordinate axes serve to determine points on this surface.On the perpendicular central axis of the comparison progressive powerspectacle lens, the power exceeds the 0.00 diopter line at a height ofapproximately y=6 mm (i.e., the spectacle wearer obtains virtually apower of 0 dpt when gazing horizontally straight-ahead); a power of 2.00diopters is achieved at approximately y=−14 mm. Accordingly, the lenspower increases by 2.00 dpt along this length of 20 mm.

FIG. 7B shows the mean surface optical power for n=1.600 of theobject-side freeform surface of the comparison progressive powerspectacle lens of FIG. 7A. The surface curvature increases continuouslyfrom top to bottom; the mean surface power value increases from 5.00 dptat y=2 mm to 6.75 dpt at y=−18 mm.

FIG. 7C shows the surface astigmatism for n=1.600 of the object-sidefreeform surface of the comparison progressive power spectacle lens ofFIG. 7A.

FIGS. 8A, 8B, and 8C show the reproduction of the comparison progressivepower spectacle lens using a GRIN material (progressive power spectaclelens according to the disclosure). In this respect, FIG. 8A shows thedistribution of the mean spherical power. From the comparison of FIGS.7A and 8A, it is possible to gather that the power increase along theperpendicular central line of the two lenses is the same. FIG. 8Billustrates the profile of the mean surface optical power and FIG. 8Cillustrates the profile of the surface astigmatism of the front surfaceof the GRIN progressive power spectacle lens according to thedisclosure. In order to allow a comparison with FIG. 7B in respect ofthe mean curvatures and with FIG. 7C in respect of the surfaceastigmatism, it was not the GRIN material that was used during thecalculation but, like previously, the material with the refractive indexof n=1.600.

The comparison of FIGS. 8B and 8C with FIGS. 7B and 7C shows that theform of the freeform surface has changed significantly: the mean surfaceoptical power (calculated with n=1.600) now decreases from the lenscenter to the edge in irregular fashion. The profile of the surfaceastigmatism no longer exhibits a typical intermediate corridor.

FIG. 9 shows the distribution of the refractive index over the spectaclelens. Here, the refractive index increases from approximately 1.60 inthe center of the lens to approximately n=1.70 in the lower region.

FIG. 10A and FIG. 10B represent the effects of using the GRIN materialwith its specific refractive index distribution and of the design of thefreeform surface for this GRIN progressive power spectacle lens on thewidth of the intermediate corridor in comparison with the comparisonprogressive power spectacle lens. The drawings show the distribution ofthe residual astigmatic aberrations in the beam path for the spectaclewearer, for a spectacle wearer with only a prescription for sphere.

In this example, the intermediate corridor, defined here by theisoastigmatism line of 1 dpt, is widened from 8.5 mm to 12 mm, i.e., byapproximately 41 percent.

FIG. 11A and FIG. 11B show cross sections through the residualastigmatism distributions from FIG. 10A and FIG. 10B. Here, theconventional relationship between increasing power and the lateralincrease in the astigmatic aberration induced thereby (similar to therelationship of the mean surface optical power to the surfaceastigmatism according to Minkwitz's theorem) becomes particularly clear.The increase of the astigmatism in the surroundings of the center of theintermediate corridor (y=−5 mm) is significantly lower for the GRINprogressive power spectacle lens according to the disclosure, eventhough the same power increase is present as in the comparisonprogressive power spectacle lens. In a manner analogous to the firstexemplary embodiment, there is a significant deviation of theastigmatism gradient of the GRIN progressive power spectacle lens fromthe behavior predicted by Minkwitz: The intermediate corridor becomessignificantly wider.

FIGS. 12A and 12B compare the contour of the front surface of the GRINprogressive power spectacle lens according to the second exemplaryembodiment with the contour of the front surface of the comparisonprogressive power spectacle lens with the aid of a sagittal heightrepresentation. FIG. 12B shows the sagittal heights of the front surfaceof the GRIN progressive power spectacle lens according to the disclosureaccording to the second exemplary embodiment and, in comparisontherewith, FIG. 12A shows the sagittal heights of the front surface ofthe comparison progressive power spectacle lens, in each case withrespect to a coordinate system tilted through −7.02 about a horizontalaxis (i.e., the vertical Y-axis of this system is tilted through −7.02°in relation to the vertical in space).

Third Exemplary Embodiment

All of the following drawings correspond in subject matter and sequenceto those of the second exemplary embodiment.

The third exemplary embodiment shows two progressive power lenses, inwhich the convergence movement of the eye when gazing at objects in theintermediate distances and at near objects, which lie straight-ahead infront of the eye of the spectacle wearer, are taken into account. Thisconvergence movement causes the visual points through the front surfaceof the spectacle lens when gazing on these points not to lie on anexactly perpendicular straight piece, but along a vertical line pivotedtoward the nose, the line being referred to as principal line of sight.

Therefore, the center of the near portion is also displaced horizontallyin the nasal direction in these examples. The examples have beencalculated in such a way that this principal line of sight lies in theintermediate corridor, centrally between the lines on the front surfacefor which the astigmatic residual aberration is 0.5 dpt (see FIGS. 16Aand 16B in this respect).

FIG. 13A shows the distribution of the mean spherical power in the beampath for the progressive power spectacle wearer for a comparisonprogressive power spectacle lens made of a standard material (refractiveindex n=1.600) with an object-side freeform surface. The back side is,again, a spherical surface with a radius of 120 mm and the center ofrotation of the eye lies 4 mm above the geometric center of thecomparison progressive power spectacle lens at a horizontal distance of25.5 mm from the back surface. The comparison progressive powerspectacle lens has a central thickness of 2.5 mm and a prismatic power1.0 cm/m base 270°, 2 mm below the geometric center. The back surface istilted in such a way that, when gazing horizontally straight-ahead, theeye-side ray is perpendicular to the back surface.

When gazing horizontally straight-ahead (i.e., for a visual pointthrough the lens of 4 mm above the geometric center), the spectaclewearer receives a mean power of 0 dpt and, when gazing through the point13 mm below the geometric center and −2.5 mm horizontally in the nasaldirection, the spectacle wearer receives a mean power of 2.00 dpt. Thatis to say, the lens power accordingly increases by approximately 2.00dpt along a length of 17 mm.

FIG. 13B shows the distribution of the mean surface optical power for arefractive index n=1.600 of the object-side freeform surface of thecomparison progressive power spectacle lens of the third exemplaryembodiment, which brings about a distribution of the mean power asillustrated in FIG. 13A. The surface curvature increases continuouslyfrom top to bottom; the mean surface power value increases from 5.00 dptat y=approximately 2 mm to 6.50 dpt at y=−12 mm.

FIG. 13C shows the surface astigmatism for n=1.600 of the object-sidefreeform surface of the comparison progressive power spectacle lens ofFIG. 13A.

FIGS. 14A, 14B, and 14C show the reproduction of the comparisonprogressive power spectacle lens using a GRIN material (progressivepower spectacle lens according to the disclosure). In this respect, FIG.14A shows the distribution of the mean spherical power. From thecomparison of FIGS. 13A and 14A, it is possible to gather that the powerincrease along the principal line of sight in the intermediate corridoris the same. FIG. 14B illustrates the profile of the mean surfaceoptical power and FIG. 14C illustrates the profile of the surfaceastigmatism of the front surface of the GRIN progressive power spectaclelens according to the disclosure. In order to allow a comparison withFIG. 13B in respect of the mean curvatures and with FIG. 13C in respectof the surface astigmatism, it was not the GRIN material that was usedduring the calculation but, like previously, the material with therefractive index of n=1.600.

The comparison of FIGS. 13B and 13C with FIGS. 14B and 14C shows thatthe form of the freeform surface has changed significantly: the meansurface optical power (calculated with n=1.600) now decreases from thelens center to the edge in irregular fashion, in order to increase againin the peripheral regions. The profile of the surface astigmatism nolonger exhibits a typical intermediate corridor.

FIG. 15 shows the distribution of the refractive index over thespectacle lens. Here, the refractive index increases from approximately1.48 in the upper region of the lens to approximately 1.70 at the heightof y=−13 in the lower region.

FIGS. 16A and 16B represent the effects of using the GRIN material withits specific refractive index distribution and of the design of thefreeform surface for this GRIN progressive power spectacle lens on thewidth of the intermediate corridor in comparison with the comparisonprogressive power spectacle lens. The drawings show the distribution ofthe residual astigmatic aberration in the beam path for the spectaclewearer, for a spectacle wearer with only a prescription for sphere.

In this third example, the intermediate corridor, defined here by theisoastigmatism line of 1 dpt, is widened from 6 mm to 9 mm, i.e., byapproximately 50 percent.

FIG. 17A and FIG. 17B show cross sections through the residualastigmatism distributions from FIG. 16A and FIG. 16B. These drawingsonce again elucidate the conventional relationship between increasingpower and the lateral increase in the astigmatic aberration inducedthereby (similar to the relationship of the mean surface optical powerto the surface astigmatism according to Minkwitz's theorem). Theincrease of the residual astigmatic aberration in the surroundings ofthe center of the intermediate corridor (y=−5 mm) is significantly loweragain for the GRIN progressive power spectacle lens according to thedisclosure, even though the same power increase is present as in thecomparison progressive power spectacle lens.

FIGS. 18A-1 and 18A-2 and FIGS. 18B1 and 18B-2 compare the contour ofthe front surface of the GRIN progressive power spectacle lens accordingto the third exemplary embodiment with the contour of the front surfaceof the comparison progressive power spectacle lens with the aid of asagittal height representation. FIGS. 18B-1 and 18B-2 show the sagittalheights of the front surface of the GRIN progressive power spectaclelens according to the disclosure according to the third exemplaryembodiment and, in comparison therewith, FIGS. 18A-1 and 18A-2 show thesagittal heights of the front surface of the comparison progressivepower spectacle lens, in each case with respect to a plane that isperpendicular to the horizontally straight-ahead direction of view.

Fourth Exemplary Embodiment

All of the following drawings correspond in subject matter and sequenceto those of the third exemplary embodiment.

The fourth exemplary embodiment shows two progressive power lenses, inwhich the convergence movement of the eye when gazing at objects in theintermediate distances and at near objects, which lie straight-ahead infront of the eye of the spectacle wearer, are taken into account. Thisconvergence movement cause the visual points through the front surfaceof the spectacle lens when gazing on these points not to lie on anexactly perpendicular straight piece, but along a vertical line pivotedtoward the nose, the line being referred to as principal line of sight.

Therefore, the center of the near portion is also displaced horizontallyin the nasal direction in these examples. The examples have beencalculated in such a way that this principal line of sight lies in theintermediate corridor, centrally between the lines on the front surfacefor which the residual astigmatic aberration is 0.5 dpt (see FIGS. 22Aand 22B in this respect).

FIG. 19A shows the distribution of the mean spherical power in the beampath for the progressive power spectacle wearer for a comparisonprogressive power spectacle lens made of a standard material (refractiveindex n=1.600) with an eye-side freeform surface. The front side is aspherical surface with a radius of 109.49 mm and the center of rotationof the eye lies 4 mm above the geometric center of the comparisonprogressive power spectacle lens at a horizontal distance of 25.1 mmfrom the back surface. The comparison progressive power spectacle lenshas a central thickness of 2.55 mm and a prismatic power 1.5 cm/m base270°, 2 mm below the geometric center. The pantoscopic tilt is 9° andthe face form angle is 5°.

When gazing horizontally straight-ahead (i.e., for a visual pointthrough the lens of 4 mm above the geometric center), the spectaclewearer receives a mean power of 0 dpt and, when gazing through the point11 mm below the geometric center and −2.5 mm horizontally in the nasaldirection, the spectacle wearer receives a mean power of 2.50 dpt. Thatis to say, the lens power accordingly increases by approximately 2.50dpt along a length of 15 mm.

FIG. 19B shows the distribution of the mean surface optical power for arefractive index n=1.600 of the eye-side freeform surface of thecomparison progressive power spectacle lens of the fourth exemplaryembodiment, which brings about a distribution of the mean power asillustrated in FIG. 19A. The surface curvature increases continuouslyfrom top to bottom; the mean surface power value increases from −5.50dpt at y=approximately 2 mm to −3.50 dpt at y=−15 mm.

FIG. 19C shows the surface astigmatism for n=1.600 of the eye-sidefreeform surface of the comparison progressive power spectacle lens ofFIG. 19A.

FIGS. 20A, 20B, and 20C show the reproduction of the comparisonprogressive power spectacle lens using a GRIN material (progressivepower spectacle lens according to the disclosure). In this respect, FIG.20A shows the distribution of the mean spherical power. From thecomparison of FIGS. 19A and 20A, it is possible to gather that the powerincrease along the principal line of sight in the intermediate corridoris the same. FIG. 20B illustrates the profile of the mean surfaceoptical power and FIG. 20C illustrates the profile of the surfaceastigmatism of the back surface of the GRIN progressive power spectaclelens according to the disclosure. In order to allow a comparison withFIG. 19B in respect of the mean curvatures and with FIG. 19C in respectof the surface astigmatism, it was not the GRIN material that was usedduring the calculation but, like previously, the material with therefractive index of n=1.600.

The comparison of FIGS. 19B and 19C with FIGS. 20B and 20C shows thatthe form of the freeform surface has changed significantly: both thedistribution of the mean surface optical power and the distribution ofthe surface astigmatism (calculated with n=1.600) no longer reveal atypical intermediate corridor.

FIG. 21 shows the distribution of the refractive index over thespectacle lens. Here, the refractive index increases from approximately1.55 in the upper lateral region of the lens to approximately n=1.64 inthe lower region.

FIGS. 22A and 22B represent the effects of using the GRIN material withits specific refractive index distribution and of the design of thefreeform surface for this GRIN progressive power spectacle lens on thewidth of the intermediate corridor in comparison with the comparisonprogressive power spectacle lens. The drawings show the distribution ofthe residual astigmatic aberrations in the beam path for the spectaclewearer, for a spectacle wearer with only a prescription for sphere. Theprincipal line of sight is depicted in both FIGS. 22A and 22B.

FIG. 23A and FIG. 23B show cross sections through the residualastigmatism distributions from FIG. 22A and FIG. 22B. These drawingsonce again elucidate the conventional relationship between increasingpower and the lateral increase in the astigmatic aberration inducedthereby (similar to the relationship of the mean surface optical powerto the surface astigmatism according to Minkwitz's theorem). Theincrease of the residual astigmatic aberration in the surroundings ofthe center of the intermediate corridor (y=−4 mm) is significantly loweragain for the GRIN progressive power spectacle lens according to thedisclosure, even though the same power increase is present as in thecomparison progressive power spectacle lens. In this fourth example, theintermediate corridor, defined here by the isoastigmatism line of 1 dpt,is widened from 4.5 mm to 6 mm, i.e., by approximately 33 percent.

FIGS. 24A and 24B compare the contour of the back surface of the GRINprogressive power spectacle lens according to the fourth exemplaryembodiment with the contour of the back surface of the comparisonprogressive power spectacle lens with the aid of a sagittal heightrepresentation. FIGS. 24B-1 and 24B-2 show the sagittal heights of theback surface of the GRIN progressive power spectacle lens according tothe disclosure according to the fourth exemplary embodiment and, incomparison therewith, FIGS. 24A-1 and 24A-2 show the sagittal heights ofthe back surface of the comparison progressive power spectacle lens, ineach case with respect to a plane that is perpendicular to thehorizontally straight-ahead direction of view.

Fifth Exemplary Embodiment

The following drawings correspond thematically to those concerning thefourth exemplary embodiment.

The fifth exemplary embodiment shows a lens designed for theprescription values of sphere −4 dpt, cylinder 2 dpt, axis 90 degrees.The prescription values stipulated in the prescription serve to correctthe visual defects of the spectacle wearer.

As in the fourth exemplary embodiment, in the fifth exemplaryembodiment, too, the convergence movement of the eye when gazing atobjects in the intermediate distances and at near objects, which liestraight-ahead in front of the eye of the spectacle wearer, are takeninto account. This convergence movement causes the visual points throughthe front surface of the spectacle lens when gazing on these points notto lie on an exactly perpendicular straight piece, but along a verticalline pivoted toward the nose, the line being referred to as principalline of sight.

Therefore, the center of the near portion is also displaced horizontallyin the nasal direction in these examples. The examples have beencalculated in such a way that this principal line of sight lies in theintermediate corridor, centrally between the lines on the front surfacefor which the residual astigmatic aberration is 0.5 dpt (see FIG. 27A inthis respect).

FIG. 25A shows the distribution of the mean spherical power in the beampath for the progressive power spectacle wearer for a progressive powerspectacle lens according to the disclosure using a GRIN material with aneye-side freeform surface. The prescription values of sphere −4 dpt,cylinder 2 dpt, axis 90 degrees have been taken into account in thedesign. The front side is, again, a spherical surface with a radius of109.49 mm and the center of rotation of the eye lies 4 mm above thegeometric center of the progressive power spectacle lens at a horizontaldistance of 25.5 mm from the back surface. The progressive powerspectacle lens according to the disclosure has a central thickness of2.00 mm and a prismatic power 1.5 cm/m base 270°, 2 mm below thegeometric center. The pantoscopic tilt is 9° and the face form angle is5°.

When gazing horizontally straight-ahead (i.e., for a visual pointthrough the lens of 4 mm above the geometric center), the spectaclewearer receives a mean power of 0 dpt and, when gazing through the point11 mm below the geometric center and −2.5 mm horizontally in the nasaldirection, the spectacle wearer receives a mean power of 2.50 dpt. Thatis to say, the lens power accordingly increases by approximately 2.50dpt along a length of 15 mm.

FIG. 25B illustrates the profile of the mean surface optical power andFIG. 25C illustrates the profile of the surface astigmatism of the backsurface of the GRIN progressive power spectacle lens according to thedisclosure of the fifth exemplary embodiment. It was not the GRINmaterial that was used during the calculation but, like previously, thematerial with the refractive index of n=1.600.

FIG. 26 shows the distribution of the refractive index over thespectacle lens. Here, the refractive index increases from approximately1.55 in the upper lateral region of the lens to approximately n=1.64 inthe lower region.

FIGS. 27A and 27B show the distribution of the residual astigmaticaberrations in the beam path for the spectacle wearer for a spectaclewearer having the prescription of sphere −4 dpt, cylinder 2 dpt, axis 90degrees. The principal line of sight is depicted in FIG. 27A. Thefigures reveal that through the use of the GRIN material with itsspecific refractive index distribution and also the design of thefreeform surface for this GRIN progressive power spectacle lens, evenfor an astigmatic prescription, it is possible to increase the width ofthe intermediate corridor in comparison with the comparison progressivepower spectacle lens.

FIG. 27B shows the cross section in the center of the intermediatecorridor (y=−4 mm) through the residual astigmatism distribution fromFIG. 27A. With the same power increase, for the GRIN progressive powerspectacle lens according to the disclosure with an astigmaticprescription, the intermediate corridor, defined here by theisoastigmatism line of 1 dpt, is widened from 4.5 mm to 6 mm, i.e., byapproximately 33 percent, compared with the comparison progressive powerspectacle lens with only a prescription for sphere.

FIG. 28 shows the sagittal heights of the back surface of the GRINprogressive power spectacle lens according to the disclosure accordingto the fifth exemplary embodiment with respect to a plane that isperpendicular to the horizontally straight-ahead direction of view.

Sixth Exemplary Embodiment

The essential steps of a method according to the disclosure for planninga GRIN progressive power spectacle lens are sketched out below:

Individual user data or application data of the spectacle wearer arecaptured in a first step. This includes the capture of (physiological)data that are assignable to the spectacle wearer and the capture of useconditions, under which the spectacle wearer will wear the progressivepower spectacles to be planned.

By way of example, the physiological data of the spectacle wearerinclude the refractive error and the accommodation capability, which aredetermined by means of a refraction measurement and which are regularlyincluded in the prescription in the form of the prescription values forsphere, cylinder, axis, prism and base, as well as addition.Furthermore, the pupillary distance and the pupil size, for example, aredetermined in different light conditions. By way of example, the age ofthe spectacle wearer is considered; this has an influence on theexpected accommodation capability and pupil size. The convergencebehavior of the eyes emerges from the pupil distance for differentdirections of view and object distances.

The use conditions include the seat of the spectacle lenses in front ofthe eye (usually in relation to the center of rotation of the eyes) andthe object distances for different directions of views, at which thespectacle wearer should see in focus. The seat of the spectacle wearerin front of the eye can be determined, for example, by capturing vertexdistance, pantoscopic tilt and lateral tilt. These data are included inan object distance model, for which a ray tracing method can beperformed.

In a subsequent step, a design plan for the spectacle lens with amultiplicity of evaluation points is set on the basis of these captureddata. The design plan comprises intended optical properties for theprogressive power spectacle lens at the respective evaluation point. Byway of example, the intended properties include the admissible deviationfrom the prescribed spherical and astigmatic power taking account of theaddition, to be precise in the manner distributed over the entireprogressive power spectacle lens as predetermined by the arrangement ofthe spectacle lens in front of the eye and by the underlying distancemodel.

Furthermore, a plan of surface geometries for the front and back surfaceand a plan for a refractive index distribution over the entire spectaclelens are set. By way of example, the front surface can be chosen to be aspherical surface and the back surface can be chosen to be a progressivesurface. Additionally, both surfaces could initially be chosen asspherical surfaces. In general, the selection of surface geometry forthe first plan merely determines the convergence (speed and success) ofthe applied optimization method below. By way of example, the assumptionshould be made that the front surface should maintain the spherical formand the back surface receives the form of a progressive surface.

The profile of chief rays through the multiplicity of evaluation pointsin accordance with the spectacle wearer beam path is determined in afurther step. Optionally, it is possible to set a local wavefront foreach of the chief rays in the surroundings of the respective chief ray.

In a subsequent step, the aforementioned optical properties of thespectacle lens are ascertained at the evaluation points by determiningan influence of the spectacle lens on the beam path of the chief raysand the local wavefronts in the surroundings of the chief ray by meansof the respective evaluation point.

In a further step, the plan of the spectacle lens is evaluated dependingon the ascertained optical properties and the individual user data.Then, the back surface and the refractive index distribution of the planof the spectacle lens are modified in view of minimizing a targetfunction,

F=E _(m) E _(n) W _(n) ^(m)(T _(n) ^(m) −A _(n) ^(m))²,

where W_(n) ^(m) represents the weighting of the optical property n atthe evaluation point m, T_(n) ^(m) represents the intended value of theoptical property n at the evaluation point m and A_(n) ^(m) representsthe actual value of the optical property n at the evaluation point m.

Expressed differently, the local surface geometry of the back surfaceand the local refractive index of the progressive power spectacle lensis modified in the respective visual beam path through the evaluationpoints until a termination criterion has been satisfied.

The GRIN progressive power spectacle lens planned in this inventivemanner can then be manufactured according to this plan.

The foregoing description of the exemplary embodiments of the disclosureillustrates and describes the present disclosure. Additionally, thedisclosure shows and describes only the exemplary embodiments but, asmentioned above, it is to be understood that the disclosure is capableof use in various other combinations, modifications, and environmentsand is capable of changes or modifications within the scope of theconcept as expressed herein, commensurate with the above teachingsand/or the skill or knowledge of the relevant art.

The term “comprising” (and its grammatical variations) as used herein isused in the inclusive sense of “having” or “including” and not in theexclusive sense of “consisting only of.” The terms “a” and “the” as usedherein are understood to encompass the plural as well as the singular.

All publications, patents and patent applications cited in thisspecification are herein incorporated by reference, and for any and allpurposes, as if each individual publication, patent or patentapplication were specifically and individually indicated to beincorporated by reference. In the case of inconsistencies, the presentdisclosure will prevail.

1-39. (canceled)
 40. A product comprising: (i) a progressive power spectacle lens or (ii) a representation of the progressive power spectacle lens having instructions for the production thereof using an additive method, the representation being stored on a non-transitory data medium as computer-readable data, or (iii) a non-transitory data medium with a virtual representation of the progressive power spectacle lens as computer-readable data having instructions for the production thereof using an additive method, wherein the progressive power spectacle lens includes: a uniform substrate having a spatially varying refractive index, a front surface, and a back surface, wherein, during use as intended, the front surface and the back surface either jointly form outer surfaces of the progressive power spectacle lens or at least one of the front surface or the back surface is exclusively provided with one or more functional coatings which do not contribute or at each point contribute less than 0.004 dpt to a spherical equivalent of a dioptric power of the progressive power spectacle lens, wherein at least one of the front surface is or the back surface is configured as a freeform surface,  wherein (a) the refractive index varies in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, wherein a distribution of the refractive index in the first spatial dimension and the second spatial dimension in all planes perpendicular to the third spatial dimension has neither point symmetry nor axial symmetry.
 41. A product comprising: (i) a progressive power spectacle lens or (ii) a representation of the progressive power spectacle lens having instructions for the production thereof using an additive method, the representation being stored on a non-transitory data medium ias computer-readable data, or (iii) a non-transitory data medium with a virtual representation of the progressive power spectacle lens as computer-readable data having instructions for the production thereof using an additive method, wherein the progressive power spectacle lens includes: a uniform substrate having a spatially varying refractive index, a front surface, and a back surface, wherein, during use as intended, the front surface and the back surface either jointly form outer surfaces of the progressive power spectacle lens or at least one of the front surface or the back surface is exclusively provided with one or more functional coatings which do not contribute or at each point contribute less than 0.004 dpt to a spherical equivalent of a dioptric power of the progressive power spectacle lens, wherein at least one of the front surface or the back surface is configured as a freeform surface,  wherein (c) the refractive index varies in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, wherein a distribution of the refractive index has no point symmetry and no axial symmetry at all.
 42. The product as claimed in claim 40, wherein the product comprises a zero viewing direction during use as intended and wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the zero viewing direction during use as intended or differs by not more than 10° from the zero viewing direction during use as intended or differs by not more than 20° from the zero viewing direction during use as intended.
 43. The product as claimed in claim 40, wherein the product comprises a principal viewing direction during use as intended and wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the principal viewing direction during use as intended or differs by not more than 10° from the principal viewing direction during use as intended or differs by not more than 20° from the principal viewing direction during use as intended.
 44. The product as claimed in claim 40, wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the direction of the normal vector of the front surface in the geometric center of the progressive power spectacle lens or differs by not more than 10° from the direction of the normal vector of the front surface in the geometric center of the progressive power spectacle lens or differs by not more than 20° from the direction of the normal vector of the front surface in the geometric center of the progressive power spectacle lens.
 45. The product as claimed in claim 40, wherein the product comprises a prismatic measurement point and wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the direction of the normal vector at the prismatic measurement point or differs by not more than 10° from the direction of the normal vector at the prismatic measurement point or differs by not more than 20° from the direction of the normal vector at the prismatic measurement point.
 46. The product as claimed in claim 40, wherein the product comprises a centration point and wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the direction of the normal vector at the centration point or differs by not more than 10° from the direction of the normal vector at the centration point or differs by not more than 20° from the direction of the normal vector at the centration point.
 47. The product as claimed in claim 40, wherein (i) the front surface is configured as the freeform surface, wherein a maximum of an absolute value of a mean curvature of the front surface is in an intermediate corridor, and/or (ii) the back surface is configured as the freeform surface, wherein a minimum of the absolute value of the mean curvature of the back surface is in the intermediate corridor, or (iii) the back surface has a spherical, rotationally symmetrically aspheric, or toric surface geometry or is a surface having two planes of symmetry and the front surface is configured as the freeform surface, wherein the maximum of the absolute value of the mean curvature of the front surface is in the intermediate corridor, or (iv) the front surface has a spherical, rotationally symmetrically aspheric, or toric surface geometry or is a surface having two planes of symmetry and the back surface is configured as the freeform surface, wherein the minimum of the absolute value of the mean curvature of the back surface is in the intermediate corridor, or (v) the back surface is not configured as the freeform surface and the front surface is configured as the freeform surface, wherein the maximum of the absolute value of the mean curvature of the front surface is in the intermediate corridor, or (vi) the front surface is not configured as the freeform surface and the back surface is configured as the freeform surface, wherein the minimum of the absolute value of the mean curvature of the back surface is in the intermediate corridor.
 48. The product as claimed in claim 40, further comprising: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, or (ii) the non-transitory data medium with the computer-readable data concerning the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has an intermediate corridor with a width and the refractive index of the progressive power spectacle lens varies in space such that the width of the intermediate corridor of the progressive power spectacle lens, at least in a section or over the entire length of the intermediate corridor, is greater than the width of the intermediate corridor in the at least one section or over the entire length of the intermediate corridor of a comparison progressive power spectacle lens with a same distribution of the spherical equivalent in the case of a same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, but with a spatially non-varying refractive index.
 49. The product as claimed in claim 48, wherein a variant of the group: horizontal section, section at half addition, horizontal section at half addition, horizontal section at half addition, horizontal section at 25% of the addition, horizontal section at 75% of the addition, horizontal section at half addition and horizontal section at 25% of the addition, horizontal section at half addition and horizontal section at 75% of the addition, horizontal section at half addition and horizontal section at 25% of the addition and horizontal section at 75% of the addition, is chosen for the at least one section.
 50. The product as claimed in claim 48, further comprising: (i) a representation, situated on the non-transitory data medium as the computer-readable data, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (ii) a representation, situated on the non-transitory data medium as the computer-readable data, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iii) a representation, situated on the non-transitory data medium as the computer-readable data, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iv) a representation, situated on the non-transitory data medium as the computer-readable data, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (v) the non-transitory data medium having the computer-readable data concerning a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vi) the non-transitory data medium having the computer-readable data concerning an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vii) the non-transitory data medium having the computer-readable data concerning a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (viii) the non-transitory data medium having the computer-readable data concerning a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has a distance portion and a near portion, and in that wherein the width of the intermediate corridor corresponds to the dimension transverse to a longitudinal direction of the intermediate corridor extending between the distance portion and near portion, within which the absolute value of the residual astigmatism lies below a predetermined limit value, which is selected within a range from the group specified below: (a) the limit value lies in the range between 0.25 dpt and 1.5 dpt, (b) the limit value lies in the range between 0.25 dpt and 1.0 dpt, (c) the limit value lies in the range between 0.25 dpt and 0.75 dpt, (d) the limit value lies in the range between 0.25 dpt and 0.6 dpt, (e) the limit value lies in the range between 0.25 dpt and 0.5 dpt, (f) the limit value is 0.5 dpt.
 51. The product as claimed in claim 40, further comprising: (i) a representation, situated on the non-transitory data medium as the computer-readable data, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, or (ii) the non-transitory data medium having the computer-readable data concerning a predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that wherein the product further includes: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (ii) a representation, situated on the non-transitory data medium as the computer-readable data, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iii) a representation, stored on the non-transitory data medium as the computer-readable data, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iv) a representation, stored on a data medium in the form of computer-readable data, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (v) the non-transitory data medium having the computer-readable data concerning a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vi) the non-transitory data medium having the computer-readable data concerning an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vii) the non-transitory data medium having the computer-readable data concerning a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (viii) the non-transitory data medium having the computer-readable data concerning a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and wherein the refractive index of the progressive power spectacle lens varies in space such that a maximum value of a residual astigmatism of the progressive power spectacle lens is less than the maximum value of the residual astigmatism of a comparison progressive power spectacle lens with a same distribution of the spherical equivalent in the case of a same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, but with a spatially non-varying refractive index.
 52. The product as claimed in claim 40, further comprising: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, or (ii) the non-transitory data medium having the computer-readable data concerning the predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the product further includes: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (ii) a representation, stored on the non-transitory data medium as the computer-readable data, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iii) a representation, stored on the non-transitory data medium as the computer-readable data, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iv) a representation, stored on the non-transitory data medium as the computer-readable data, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (v) the non-transitory data medium having the computer-readable data concerning a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vi) the non-transitory data medium having the computer-readable data concerning an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vii) the non-transitory data medium having the computer-readable data concerning a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (viii) the non-transitory data medium having the computer-readable data concerning a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens includes an intermediate corridor and a principal line of sight, and where in the refractive index of the progressive power spectacle lens varies in space such that for a predetermined residual astigmatism value A_(res,lim) of the group (a) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 1.5 dpt, (b) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 1.0 dpt, (c) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 0.75 dpt, (d) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 0.6 dpt, (e) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 0.5 dpt, (f) the residual astigmatism value A_(res,lim) is 0.5 dpt on a horizontal section at a narrowest point of the intermediate corridor or for a horizontal section through a point on the principal line of sight at which the half addition is achieved, the following relationship applies within a region with a horizontal distance of 10 mm on both sides of the principal line of sight: $B > {c \times \frac{A_{{res},\lim}}{{grad}\mspace{14mu} W}}$ wherein grad W describes the power gradient of the spherical equivalent in the direction of the principal line of sight of the progressive power spectacle lens at the narrowest point of the intermediate corridor on the principal line of sight or in a point on the principal line of sight at which the half addition is achieved, B describes the width of the region in the progressive power spectacle lens in which the residual astigmatism is A_(res)≤A_(res,lim), where c is a constant selected from the group: (a) 1.0<c, (b) 1.1<c, (c) 1.2<c, or (d) 1.3<c.
 53. A product comprising: (i) a progressive power spectacle lens or (ii) a representation of the progressive power spectacle lens having instructions for the production thereof using an additive method, the representation being stored on a non-transitory data medium as computer-readable data, or (iii) the non-transitory data medium having a virtual representation of the progressive power spectacle lens as computer-readable data and having instructions for the production thereof using an additive method, wherein the progressive power spectacle lens has: a front surface; a back surface; and a spatially varying refractive index, wherein at least one of the front surface or the back surface is configured as a freeform surface, the freeform surface being configured as a progressive surface, wherein the progressive power spectacle lens is made of a substrate having no individual layers and having the front surface, the back surface, and the spatially varying refractive index, wherein the substrate has at least one of a front surface coating including one or more individual layers or a back surface coating including one or more individual layers, wherein a difference between the spherical equivalent measured at each point on the front surface of the progressive power spectacle lens with the at least one of the front surface coating or the back surface coating and the spherical equivalent measured at each corresponding point on the front surface of a comparison progressive power spectacle lens without the front surface coating and without the back surface coating but with an identical substrate is less than a value from the group specified below: (a) the difference value is less than 0.001 dpt (b) the difference value is less than 0.002 dpt (c) the difference value is less than 0.003 dpt (d) the difference value is less than 0.004 dpt  and wherein (b) the refractive index varies in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, wherein the distribution of the refractive index in the first spatial dimension and the second spatial dimension in all planes perpendicular to the third spatial dimension has neither point symmetry nor axial symmetry.
 54. A product comprising: (i) a progressive power spectacle lens or (ii) a representation of the progressive power spectacle lens having instructions for the production thereof using an additive method, the representation being stored on a data medium as computer-readable data, or (iii) the non-transitory data medium having a virtual representation of the progressive power spectacle lens as the computer-readable data and having instructions for the production thereof using an additive method, wherein the progressive power spectacle lens has: a front surface; a back surface; and a spatially varying refractive index, wherein at least one of the front surface or the back surface is configured as a freeform surface, wherein the freeform surface is configured as a progressive surface, wherein the progressive power spectacle lens is made of a substrate having no individual layers and having the front surface, the back surface, and the spatially varying refractive index, wherein the substrate has at least one of a front surface coating including one or more individual layers or a back surface coating including one or more individual layers, wherein a difference between a spherical equivalent measured at each point on the front surface of the progressive power spectacle lens with the at least one of the front surface coating or the back surface coating and the spherical equivalent measured at each corresponding point on the front surface of a comparison progressive power spectacle lens without the front surface coating and without the back surface coating but with an identical substrate is less than a value from the group specified below: (a) the difference value is less than 0.001 dpt (b) the difference value is less than 0.002 dpt (c) the difference value is less than 0.003 dpt (d) the difference value is less than 0.004 dpt  and wherein (c) the refractive index varies in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, wherein a distribution of the refractive index has no point symmetry and no axial symmetry at all.
 55. The product as claimed in claim 53, further comprising a zero viewing direction during use as intended, wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the zero viewing direction during use as intended or differs by not more than 10° from the zero viewing direction during use as intended or differs by not more than 20° from the zero viewing direction during use as intended.
 56. The product as claimed in claim 53, further comprising a principal viewing direction during use as intended, wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the principal viewing direction during use as intended or differs by not more than 10° from the principal viewing direction during use as intended or differs by not more than 20° from the principal viewing direction during use as intended.
 57. The product as claimed in claim 53, wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the direction of the normal vector of the front surface in the geometric center of the progressive power spectacle lens or differs by not more than 10° from the direction of the normal vector of the front surface in the geometric center of the progressive power spectacle lens or differs by not more than 20° from the direction of the normal vector of the front surface in the geometric center of the progressive power spectacle lens.
 58. The product as claimed in claim 53, further comprising a prismatic measurement point, wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the direction of the normal vector at the prismatic measurement point or differs by not more than 10° from the direction of the normal vector at the prismatic measurement point or differs by not more than 20° from the direction of the normal vector at the prismatic measurement point.
 59. The product as claimed in claim 53, further comprising a centration point, wherein the third spatial dimension in case (a) extends in a direction which differs by not more than 5° from the direction of the normal vector at the centration point or differs by not more than 10° from the direction of the normal vector at the centration point or differs by not more than 20° from the direction of the normal vector at the centration point.
 60. The product as claimed in claim 53, wherein the progressive power spectacle lens further comprises an intermediate corridor, wherein (i) the front surface is configured as the freeform surface, wherein the mean curvature has a maximum in the intermediate corridor, and/or (ii) the back surface is configured as the freeform surface, wherein the mean curvature has a minimum in the intermediate corridor, or (iii) the back surface has a spherical, rotationally symmetrically aspheric, or toric surface geometry and the front surface is configured as the freeform surface, wherein the maximum of the absolute value of the mean curvature of the front surface is in the intermediate corridor, or (iv) the front surface has a spherical, rotationally symmetrically aspheric, or toric surface geometry and the back surface is configured as the freeform surface, wherein the minimum of the absolute value of the mean curvature of the back surface is in the intermediate corridor, or (v) the back surface is not configured as the freeform surface and the front surface is configured as the freeform surface, wherein the maximum of the absolute value of the mean curvature of the front surface is in the intermediate corridor, or (vi) the front surface is not configured as the freeform surface and the back surface is configured as the freeform surface, wherein the minimum of the absolute value of the mean curvature of the back surface is in the intermediate corridor.
 61. The product as claimed in claim 53, further comprising: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, or (ii) the non-transitory data medium having the computer-readable data concerning a predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has an intermediate corridor with a width and the refractive index of the progressive power spectacle lens varies in space such that the width of the intermediate corridor of the progressive power spectacle lens, at least in a section or over the entire length of the intermediate corridor, is greater than the width of the intermediate corridor of a comparison progressive power spectacle lens with a same distribution of the spherical equivalent in the case of a same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, but with a spatially non-varying refractive index.
 62. The product as claimed in claim 61, wherein a variant of the group: horizontal section, section at half addition, horizontal section at half addition, horizontal section at half addition and horizontal section at 25% of the addition, horizontal section at half addition and horizontal section at 75% of the addition, horizontal section at half addition and horizontal section at 25% of the addition and horizontal section at 75% of the addition, is chosen for the at least one section.
 63. The product as claimed in claim 61, further comprising: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (ii) a representation, stored on the non-transitory data medium as the computer-readable data, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iii) a representation, stored on the non-transitory data medium as the computer-readable data, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iv) a representation, stored on the non-transitory data medium as the computer-readable data, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (v) the non-transitory data medium having the computer-readable data concerning a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vi) the non-transitory data medium having the computer-readable data concerning an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vii) the non-transitory data medium having the computer-readable data concerning a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (viii) the non-transitory data medium having the computer-readable data concerning a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has a distance portion and a near portion, and wherein the width of the intermediate corridor corresponds to the dimension transverse to a longitudinal direction of the intermediate corridor extending between the distance portion and near portion, within which the absolute value of the residual astigmatism lies below a predetermined limit value, which is selected within a range from the group specified below: (a) the limit value lies in the range between 0.25 dpt and 1.5 dpt, (b) the limit value lies in the range between 0.25 dpt and 1.0 dpt, (c) the limit value lies in the range between 0.25 dpt and 0.75 dpt, (d) the limit value lies in the range between 0.25 dpt and 0.6 dpt, (e) the limit value lies in the range between 0.25 dpt and 0.5 dpt, (f) the limit value is 0.5 dpt.
 64. The product as claimed in claim 53, further comprising: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, or (ii) the non-transitory data medium having computer-readable data concerning a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the product further includes: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (ii) a representation, stored on the non-transitory data medium as the computer-readable data, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iii) a representation, stored on the non-transitory data medium as the computer-readable data, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iv) a representation, stored on the non-transitory data medium as the computer-readable data, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (v) the non-transitory data medium having computer-readable data concerning a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vi) the non-transitory data medium having computer-readable data concerning an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vii) the non-transitory data medium having computer-readable data concerning a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (viii) the non-transitory data medium having computer-readable data concerning a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the refractive index of the progressive power spectacle lens varies in space such that the maximum value of the residual astigmatism of the progressive power spectacle lens is less than the maximum value of the residual astigmatism of a comparison progressive power spectacle lens with a same distribution of the spherical equivalent in the case of a same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, but with a spatially non-varying refractive index.
 65. The product as claimed in claim 53, further comprising: (i) a representation, stored on the non-transitory data medium as computer-readable data, of a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, or (ii) the non-transitory data medium having computer-readable data concerning a predetermined arrangement of the progressive power spectacle lens in front of an eye of a progressive power spectacle wearer, wherein the progressive power spectacle lens has a distribution of a spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, in that the product further includes: (i) a representation, stored on the non-transitory data medium as the computer-readable data, of a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (ii) a representation, stored on the non-transitory data medium as the computer-readable data, of an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iii) a representation, stored on the non-transitory data medium as the computer-readable data, of a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (iv) a representation, stored on the non-transitory data medium as the computer-readable data, of a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (v) the non-transitory data medium having computer-readable data concerning a residual astigmatism distribution for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vi) the non-transitory data medium having computer-readable data concerning an astigmatic power distribution, required for a full correction, for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (vii) the non-transitory data medium having computer-readable data concerning a prescription and an object distance model for the predetermined arrangement of the progressive power spectacle lens in front of the eye of a progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, and/or (viii) the non-transitory data medium having computer-readable data concerning a distribution of the spherical equivalent for the predetermined arrangement of the progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, for whom the progressive power spectacle lens is intended, wherein the progressive power spectacle lens has an intermediate corridor and a principal line of sight, and wherein the refractive index of the progressive power spectacle lens varies in space such that for a predetermined residual astigmatism value A_(res,lim) of the group (a) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 1.5 dpt, (b) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 1.0 dpt, (c) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 0.75 dpt, (d) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 0.6 dpt, (e) the residual astigmatism value A_(res,lim) lies in the range between 0.25 dpt and 0.5 dpt, (f) the residual astigmatism value A_(res,lim) is 0.5 dpt on a horizontal section at a narrowest point of the intermediate corridor or for a horizontal section through the point on the principal line of sight at which the half addition is achieved, the following relationship applies within a region with a horizontal distance of 10 mm on both sides of the principal line of sight: $B > {c \times \frac{A_{{res},\lim}}{{grad}\mspace{14mu} W}}$ wherein grad W describes a power gradient of the spherical equivalent of the progressive power spectacle lens at the narrowest point of the intermediate corridor on the principal line of sight or in the point on the principal line of sight at which the half addition is achieved, B describes the width of the region in the progressive power spectacle lens in which the residual astigmatism is A_(res)≤A_(res,lim), wherein c is a constant selected from the group: (a) 1.0<c, (b) 1.1<c, (c) 1.2<c, or (d) 1.3<c.
 66. A computer-implemented method for designing a progressive power spectacle lens having a front surface, a back surface, and a spatially varying refractive index, wherein at least one of the front surface or the back surface is configured as a progressive surface, the method comprising: calculating optical properties of the progressive power spectacle lens with a ray tracing method at a plurality of evaluation points, at which visual rays pass through the progressive power spectacle lens; setting at least one intended optical property for the progressive power spectacle lens at the respective evaluation point; setting a design for the progressive power spectacle lens, wherein the design includes a representation of a local surface geometry of the progressive surface and a local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points; modifying the design of the progressive power spectacle lens in view of an approximation of the at least one intended optical property of the progressive power spectacle lens, wherein the modifying includes modifying the representation of the local surface geometry of the progressive surface and the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein the at least one intended optical property includes an intended residual astigmatism of the progressive power spectacle lens, wherein the progressive surface and the local refractive index are modified according to at least one of the specifications from the following group of specifications: (i) the progressive surface is modified freely in two spatial dimensions and the local refractive index is modified freely in at least two spatial dimensions, (ii) the progressive surface is modified freely in one or in two spatial dimensions and the local refractive index is modified freely in three spatial dimensions, (iii) the progressive surface is modified freely in two spatial dimensions and the local refractive index is modified freely in two spatial dimensions, and (iv) the progressive surface is modified freely in two spatial dimensions and the local refractive index is modified freely in three spatial dimensions.
 67. The method as claimed in claim 66, wherein the progressive surface is modified such that a freeform surface arises which has neither point symmetry nor axial symmetry, and wherein the local refractive index is modified such that: (a) the refractive index varies only in a first spatial dimension and in a second spatial dimension, and is constant in a third spatial dimension, such that a distribution of the refractive index in the first spatial dimension and the second spatial dimension has neither point symmetry nor axial symmetry, or (b) the refractive index varies in the first spatial dimension, the second spatial dimension, and the third spatial dimension, such that a distribution of the refractive index in the first spatial dimension and the second spatial dimension in all planes perpendicular to the third spatial dimension has neither point symmetry nor axial symmetry, or (c) the refractive index varies in the first spatial dimension, the second spatial dimension, and the third spatial dimension, such that a distribution of the refractive index in the progressive power spectacle lens has no point symmetry and no axial symmetry at all.
 68. The method as claimed in claim 66, wherein the at least one intended optical property of the progressive power spectacle lens is derived (i) from a corresponding intended optical property for a progressive power spectacle lens with a spatially non-varying refractive index and/or (ii) from a corresponding optical property of a progressive power spectacle lens with a spatially non-varying refractive index, or wherein the intended residual astigmatism of the progressive power spectacle lens is derived (i) from an intended residual astigmatism for a progressive power spectacle lens with a spatially non-varying refractive index and/or (ii) from a residual astigmatism of a progressive power spectacle lens with a spatially non-varying refractive index.
 69. The method as claimed in claim 68, wherein the at least one intended optical property of the progressive power spectacle lens in a central intermediate portion between the distance portion and the near portion is reduced vis-à-vis (i) the corresponding intended optical property for the progressive power spectacle lens with a spatially non-varying refractive index or (ii) the corresponding optical property of the progressive power spectacle lens with a spatially non-varying refractive index, or wherein the intended residual astigmatism of the progressive power spectacle lens in a central intermediate portion between distance portion and near portion is reduced vis-à-vis (i) the intended residual astigmatism for the progressive power spectacle lens with a spatially non-varying refractive index or (ii) the residual astigmatism of the progressive power spectacle lens with a spatially non-varying refractive index.
 70. The method as claimed in claim 69, wherein the intended residual astigmatism of the progressive power spectacle lens in a central intermediate portion between distance portion and near portion is reduced in a region around the principal line of sight, and wherein the region comprises a horizontal distance on both sides from the group (a) 5 mm from the principal line of sight, (b) 10 mm from the principal line of sight, or (c) 20 mm from the principal line of sight.
 71. The method as claimed in claim 66, wherein the modification of the design of the progressive power spectacle lens is implemented in view of a minimization of a target function $F = {\sum\limits_{m}{\sum\limits_{n}{W_{n}^{m}\left( {T_{n}^{m} - A_{n}^{m}} \right)}^{2}}}$ where W_(n) ^(m) represents the weighting of the optical property n at the evaluation point m, T_(n) ^(m) represents the intended value of the optical property n at the evaluation point m, and A_(n) ^(m) represents the actual value of the optical property n at the evaluation point m.
 72. The method as claimed in claim 66, wherein an intended residual astigmatism is predetermined for at least one evaluation point, the intended residual astigmatism being less than the theoretically achievable residual astigmatism at the at least one corresponding evaluation point on a comparison progressive power spectacle lens with the same distribution of the spherical equivalent and the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, but with a spatially non-varying refractive index, and in that modifying the representation of the local surface geometry of the progressive surface and of the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points is only terminated if the residual astigmatism at the at least one evaluation point, achieved for the designed progressive power spectacle lens, is less than the theoretically achievable residual astigmatism at the at least one corresponding evaluation point on the comparison progressive power spectacle lens.
 73. The method as claimed in claim 66, wherein modifying the representation of the local surface geometry of the progressive surface and of the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points is implemented with the stipulation that the maximum value of the residual astigmatism of the progressive power spectacle lens is less than the maximum value of the residual astigmatism of a comparison progressive power spectacle lens with the same distribution of the spherical equivalent and the same arrangement of the comparison progressive power spectacle lens in front of the eye of the progressive power spectacle wearer, but with a spatially non-varying refractive index.
 74. The method as claimed in claim 66, wherein designing the progressive power spectacle lens results in a progressive power spectacle lens comprising: (i) a progressive power spectacle lens or (ii) a representation of the progressive power spectacle lens having instructions for the production thereof using an additive method, the representation being stored on a non-transitory data medium as computer-readable data, or (iii) a non-transitory data medium with a virtual representation of the progressive power spectacle lens as computer-readable data having instructions for the production thereof using an additive method, wherein the progressive power spectacle lens includes: a uniform substrate having a spatially varying refractive index, a front surface, and a back surface, wherein, during use as intended, the front surface and the back surface either jointly form outer surfaces of the progressive power spectacle lens or at least one of the front surface or the back surface is exclusively provided with one or more functional coatings which do not contribute or at each point contribute less than 0.004 dpt to a spherical equivalent of a dioptric power of the progressive power spectacle lens, wherein at least one of the front surface is or the back surface is configured as a freeform surface, wherein the refractive index varies in a first spatial dimension and in a second spatial dimension and in a third spatial dimension, wherein a distribution of the refractive index in the first spatial dimension and the second spatial dimension in all planes perpendicular to the third spatial dimension has neither point symmetry nor axial symmetry.
 75. A computer program having program code for carrying out all method steps as claimed in claim 66 when the computer program is loaded on a computer and/or executed on a computer.
 76. A computer-readable medium comprising a computer program as claimed in claim
 75. 77. A method for producing, by way of an additive method, a progressive power spectacle lens as claimed in claim
 40. 78. A method for producing a progressive power spectacle lens, comprising a method as claimed in claim 66 and manufacturing of the progressive power spectacle lens according to the design.
 79. The method as claimed in claim 78, wherein the progressive power spectacle lens is manufactured using an additive method.
 80. A computer having a processor and a non-transitory memory in which a computer program as claimed in claim 75 is stored, the computer being configured to carry out a method comprising: calculating optical properties of the progressive power spectacle lens with a ray tracing method at a plurality of evaluation points, at which visual rays pass through the progressive power spectacle lens; setting at least one intended optical property for the progressive power spectacle lens at the respective evaluation point; setting a design for the progressive power spectacle lens, wherein the design includes a representation of a local surface geometry of the progressive surface and a local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points; modifying the design of the progressive power spectacle lens in view of an approximation of the at least one intended optical property of the progressive power spectacle lens, wherein the modifying includes modifying the representation of the local surface geometry of the progressive surface and the local refractive index of the progressive power spectacle lens in the respective visual beam path through the evaluation points, wherein the at least one intended optical property includes an intended residual astigmatism of the progressive power spectacle lens, wherein the progressive surface and the local refractive index are modified according to at least one of the specifications from the following group of specifications: (i) the progressive surface is modified freely in two spatial dimensions and the local refractive index is modified freely in at least two spatial dimensions, (ii) the progressive surface is modified freely in one or in two spatial dimensions and the local refractive index is modified freely in three spatial dimensions, (iii) the progressive surface is modified freely in two spatial dimensions and the local refractive index is modified freely in two spatial dimensions, and (iv) the progressive surface is modified freely in two spatial dimensions and the local refractive index is modified freely in three spatial dimensions. 